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Method of Formation of Trochosphere in Serpula. By H. W. Conn,
Gill in Neptunea. By H. L. Osborn,
On the Presence of an Intra-cellular Digestion in Salpa. By C. S. Dolley,
On the Structure and Affinities of Phytoptus. By J. P. McMurrich, Report of the University Archæological Society. By A. L. Frothingham,
REPORTS OF RECENT ADDRESSES, PAPERS, ETC.:
On the Place of the Science of Hygiene in a Liberal Education. By J. S. Billings,
On a Philological Expedition to Canada. By A. M. Elliott,
The Johns Hopkins University Circulars are printed by Messrs. JOHN MURPHY & CO., 182 West Baltimore Street, Baltimore, from whom single copies may be obtained. They may also be procured, as soon as published, from Messrs. CUSHINGS & BAILEY, No. 262 West Baltimore Street, Baltimore.
CHESAPEAKE ZOOLOGICAL LABORATORY.
REPORT OF THE DIRECTOR FOR THE YEAR 1884. [Reprinted from the Ninth Annual Report of the Johns Hopkins University]. To the President of the Johns Hopkins University:
SIR: I take pleasure in handing to you, at your request, the report of the seventh annual session of the marine laboratory of the University.
The laboratory was open for research, at Beaufort, North Carolina, from June 1st to September 19th, and its facilities were used by the following naturalists:
W. K. BROOKS, Director.
H. W. Conn, Assistant in charge.
E. A. Andrews, Fellow J. H. U.
Wm. Bateson, University of Cambridge, England.
H. H. Donaldson, J. H. U.
E. A. Hartwell, Teacher, Fitchburg, Mass.
G. F. Kemp, J. H. U.
J. Nelson, J. H. U.
H. F. Nachtrieb, Fellow J. H. U.
H. L. Osborn, Instructor in Zoology, Purdue University, Lafayette, Ind.
Owing to the illness of the director he was able to spend only one month at the laboratory, and it was, for two months, in charge of H. W. Conn, Ph. D., Professor of Zoology at the Wesleyan University, Middletown, Conn. Our experiment, of a year since, in the Chesapeake Bay, has demonstrated that Beaufort is the best available locality for our work, and our outfit was accordingly moved back from Hampton to Beaufort, in June, and the house which we had occupied in 1880-81 and '82 was again rented for occupation as a laboratory. The expenses of removal, together with the illness of the director, compelled us to make our season much shorter than usual, and the laboratory was occupied for only fifteen weeks.
The building at Beaufort furnishes accommodations for only six persons, and as our party of ten crowded it so much as to hamper our work I was compelled to refuse several applicants.
The following subjects among others were studied by the members of the party: The embryology of Echinoderms; the systematic zoology and anatomy and embryology of Annelids; the embryology of Medusae. Dr. Conn has completed his work on the development of Thalassema, and his paper is ready for publication. He has also made many additions to a subject upon which he has been engaged for three years past,graph upon the Crabs of Beaufort. This work is now nearly completed and ready for publication, and will form a large volume with about twenty-five quarto plates. He has also studied the development of Serpula, and an abstract of his observations is now in press. The most important points are that the blastopore elongates and closes in such a manner that one extremity becomes the mouth and the other the anus, while the closed lips form the ventral surface. Mr. Conn has also prepared a paper on larval forms, which is to appear in the Studies from the Biological Laboratory.
Dr. Donaldson was occupied for three months in the study of the physiology of marine invertebrates. He made many experiments to determine the relative susceptibility of the different classes of invertebrates to poisons of vegetable origin. He also carried on a series of experiments to determine whether the current theory of digestion in the Actinozoa is correct. These experiments failed to support the theory.
The results of Mr. Bateson's work upon Balanoglossus last year, were published in England last winter, and were regarded as of such importance that a grant of money was given by the Royal Society, to enable him to return to Beaufort this season and complete them. His more recent researches seem to show that Balanoglossus presents many features of relationship to the Echinoderms and also many points of resemblance to the Vertebrates. An abstract of his conclusions was read at the Montreal meeting of the British Association.
Dr. Osborn has studied the embryology of Fulgur and Neptunia, and a short abstract of his results is now in press. A longer illustrated paper will be ready for publication this winter. His results show that the gill of Neptunia arises as a series of perfectly simple folds, upon the outer surface of the animal, and before the mantle cavity is formed, and as the mantle cavity is formed these folds are carried into it. He believes that this is the primitive condition of the gills of Gasteropods, and that the formation of a
"ctenidium" is secondary. He has also studied the origin of the body cavity and reproductive organs of Gasteropods.
The early stages of Teleosts, and of Limulus have also been studied. I have made many additions to my notes on the Medusae of Beaufort, and my monograph upon this subject, upon which I have been engaged for five years, is now sufficiently advanced for publication, as soon as a publisher can be found. It will form a large volume, with about thirty quarto plates. I have now in press an abstract of my observations, made this summer upon the embryology of Eutimia. The following are some of the more important points. Delamination takes place over the whole inner surface of the blastoderm, and the digestive cavity is not obliterated. After the endoderm has been formed, the ectoderm becomes deeply invaginated, to form the adhesive gland of the planula. The planula does not become converted into a hydranth, but becomes a root, from which hydranths are formed by budding.
An illustrated paper upon the embryology of Eutimia and Liriope is now in preparation for the Studies from the Biological Laboratory, and it will be ready for publication this winter.
I was also able this summer to make a few observations upon the metamorphosis of Stomatopods, and these will be incorporated in my report on the Stomatopods of the Challenger Expedition, which will be ready for the press in March, 1885.
I have also in preparation, a paper, based on observations made this summer, on the origin of alternation in hydroids. This will be ready for publication in the Studies this winter, and I shall give facts which I believe to show that in this group, alternation has not originated through polymorphism, or division of labor, but through the asexual multiplication of immature larvae.
The following papers, based upon researches which are carried on at the marine laboratory have appeared since my last report, and five or six other papers are now in press, and will appear immediately.
On the Gill in some forms of Prosobranchiate Molluscs, by H. L. Osborn. Studies from the Biological Laboratory, vol. iii, no. 1, with three plates. Life History of Thalassema, (abstract), by H. W. Conn. Studies from the Biological Laboratory, vol. iii, no. 1, with one plate.
The Significance of the Larval Skin of Decapods, by H. W. Conn. Studies from the Biological Laboratory, vol. iii, no. 1, with two plates. On the Osteology of Syngnathus Peckeanus, by J. P. McMurrich. University Circulars, iii, 27.
An Instance of Sexual Variation in Crustacea, by II. W. Conn. University Circulars, iii, 27.
Abstract of Observations on the Development of Balanoglossus, by Wm. Bateson. University Circulars, iii, 27.
On the Osteology and Development of Syngnathus Peckeanus, by J. Playfair McMurrich. Quart. Journ. Mic. Sc., vol. 23, (October,) 623–650, with two plates.
Upon the Ears of Fishes, with reference to the Function of Equilibrium, by II. Sewall. Journal of Physiology, iv, 339.
The Early Stages in the Development of Balanoglossus, by Wm. Bateson. Quart. Journ. Mic. Science, no. xciv, 208, with four plates.
Dr. H. J. Rice, a former Fellow of the University, writes that he has, in a pond at Cold Spring Harbor, a fine set of young oysters, which he has reared from the egg by methods which were first made known at the laboratory.
environment causes an increase in the number of births of female children, while an unfavorable environment causes an increase in the number of male births.
His evidence seems to prove that we must accept his conclusion as a scientific generalization, and every one will recognize its very great value. I wish however to say a few words regarding its significance, for I believe that it is only a part of a still wider generalization, and that its true meaning can be seen only when it is viewed as a part of a still more fundamental natural law.
If while living under favorable conditions of life, a species is able to prosper and multiply with few males, or even in the case of many animals and plants, with no males at all, multiplying by parthenogenesis or by asexual reproduction; why should males become necessary when the environment becomes unfavorable?
I believe that we have, in this fact which is so well brought out in Düsing's papers, an adjustment, which has been evolved by natural selection, for the purpose of securing variation when it is needed.
I have attempted to show, from another sort of evidence, that the two sexual elements have, by division of labor, acquired, in all the higher plants, and in most of the metazoa, specialized functions; and that the male cell causes variation, while the ovum transmits the hereditary characteristics of the species.
My reasons for this conclusion, are briefly as follows:
1. The homology between the ovum and the male cell is no reason for believing that their functions are now alike, for it only shows that they were alike at some time in the past.
2. The possibility of parthenogenesis shows that the ovum can transmit all the established characteristics of the species.
3. The study of reciprocal crosses shows that the ovum and the male cell do not have the same influence, and gives many reasons for believing that the ovum transmits established characteristics, while the male cell transmits more recent modifications.
4. When a female hybrid is crossed with the male of either one of the pure parent forms, the children are less variable than those which are born from a pure female crossed with a male hybrid.
5. Organisms born from fertilized eggs or seeds are very much more variable than those which are produced asexually, and the parthenogenetic bees are the least variable of domesticated animals.
6. A variation which first appears in a male is much more likely to become hereditary than one which first appears in a female.
7. Organs which are confined to males, or which are of more functional importance in males than in females, are very much more variable than organs which are confined to females, or organs which are of more functional importance in females than in males.
8. Throughout the whole animal kingdom, with very few exceptions, we find, wherever the sexes are separate and different from each other, the males of allied species differ more from each other than the females do, and the adult male differs from the young more than the female does.
9. We also find that males are more variable than females, and that the male leads and the female follows, in the evolution of new species. This cannot be due to sexual selection, for it holds true, to a remarkable degree, in domestic pigeons, which are paired by the breeder, and are not selected, as fowls are, for the sake of any sexual peculiarity.
I believe that it is shown by these facts, and by many others, that the function of the ovum is to transmit the characteristics of the species, and to hold on to what has been acquired in the past; that the union of two sexual elements has been evolved for the purpose of securing variability; and that the male element has gradually acquired, by division of labor, the peculiar function of exciting variability to meet changes in the condition of life.
Now it is plain that, so long as the conditions of life remain favorable there is no need for variation, but whenever any unfavorable change takes place variation becomes necessary in order to restore the harmony between the organism and its environment.
If my view is true, we have in Düsing's results, an exemplification of the action of one of the most grand and beautiful and far-reaching of all the adjustments which have ever been discovered in nature; an adaptation by means of which each organism remains unchanged so long as no change is needed, while it begins to vary whenever variation and race modification are called for.
The excess of male births among captive birds of prey and carnivorous mammals, and in uncivilized human races, which have been suddenly thrown into contact with the civilization which has been the growth of thousands of years in Europe, is to be regarded as the last effort of nature to produces a modification which shall fit them for their new surrounding. It is true that Düsing himself gives a different explanation, and says that the excess of male births, under unfavorable conditions is for the purpose of preventing close inter-breeding. This is no doubt true, but I believe that it is only a part of the truth.
He says that inter-breeding causes decreased fertility, small size, and general loss of vitality and vigor, and that the purpose of crossing is to prevent this. He shows that the evil effects are greatest when the environment is unfavorable, and that a very favorable environment may entirely overbalance them. Crossing is therefore most necessary and important when the conditions of life are least favorable, and least important when they are most favorable, and an organism may, under a very favorable environment, multiply asexually or by parthenogenesis for an indefinite number of generations, although males and fertilized eggs appear as soon as the season of prosperity comes to an end.
This is all true, but we must remember that an injurious quality cannot be evolved by natural selection, and that the injurious effects of interbreeding cannot be primary. The property which has been evolved is the usefulness of crossing, and the injurious effects of inter-breeding are secondary.
Now why should crossing be more advantageous under an unfavorable than under a favorable environment? Clearly because crossing gives variability, and because variation is not advantageous when everything else is favorable, while it is advantageous when other things are unfavorable.
If two species or varieties are living under the same unfavorable conditions of life, and the crossed offspring are the most vigorous and fertile in the one, while the children of closely related parents are most fertile in the other, the establishment of a hereditary favorable variation will be much more probable in the first than in the second, and the chances are that the first will ultimately exterminate the second. If, however, the conditions of life are favorable and no variation is needed, the products of a cross will have no advantage, and will not be thus selected.
Again, it is for the advantage of the species that all the individuals shall be vigorous and fertile, unless there is some especial reason why some of them should be weak and infertile. When the conditions of life are favorable, there is no such reason, and all are alike fertile; but when the conditions become unfavorable, variation is needful; and it is therefore advantageous, to species as a whole, that those individuals in which there is most chance of variation,—those born from a cross-shall be most healthful and prolific; and those where least variation can be expected, least prolific.
Hence we find that, where the conditions of life are very favorable, the children of closely related parents, or those with only one parent, or those born asexually, are as strong and prolific as those born from widely different parents; and we also find that males are scarce, or even absent.
When the conditions of life are unfavorable, blood relations become infertile, an excess of males is produced, and the children of a cross are peculiarly prolific.
Method of Formation of Trochosphere in Serpula. By H. W. CONN.
Very few of the Annelids have a development which seems to be primitive. A great majority show undoubted evidence of a great modification in their embryology, so great as usually to give no evidence of the history of the group. There are a few, however, which for some reason have escaped this modifying influence, and still give us indications of their early history. Among these is Serpula. The development of Serpula has hitherto been studied by a single naturalist, Stossich, who published an account in 1878, so peculiar in some respects as to cause it to be held in question. Although his results have been incorporated into text books, it has yet remained desirable to investigate the matter further. On two points, in particular, have the results of Stossich been questioned. He described a regular complete segmentation, a type nowhere else found among the Annelids. (It has since been observed in several forms). But
the most peculiar point according to the work of Stossich, was the history of the blastopore, which is stated to become the anus. In some animals it is true that this undoubtedly occurs, but in no other Annelid is it known, and this history in Serpula, whose history is known to be primitive, is highly remarkable.
During the last summer I have been able, with the assistance of Mr. Andrews, to investigate these and many other points with very interesting results. In the main Stossich is right. The segmentation is regular and complete, and in most of the other minor points the work this summer confirmed the previous results. But the history of the blastopore is very different from that described by Stossich, and is in brief as follows. A regular segmentation is followed by a typical invagination, giving rise to a gastrula. A band of cilia now makes its appearance around the blastopore and a tuft of sensory cilia at the opposite end. Now that part of the body within the circumblastoporal ciliated ring, and therefore containing the blastopore, begins to elongate obliquely, causing an elongation of the blastopore. The axis of this elongation does not fall through the centre of the blastopore, but through one edge of it, and the elongation is therefore such that one end of the elongated blastopore remains near the ring of cilia while the other is carried away at the end of the elongated portion of the body. As this elongation progresses the blastopore, which has become drawn out into a long slit, closes, and its lips fusing together become what proves to be the ventral median line of the full grown larva. The endoderm is entirely within the body cavity, connected with the ectoderm, however, throughout the whole extent of the closed blastopore. Soon the two extremities of this closed blastopore open again, the one near the ciliated band becoming the mouth, the other eventually becoming the anus, while the endoderm between these two points loses all connection with the ectoderm, except at the mouth and anus, and becomes hollowed out to form the alimentary canal. The blastopore is not, therefore, converted into the anus as Stossich asserts, but it elongates, one extremity eventually becoming the mouth, the other the anus, while the intermediate portion closes to form the median ventral line of the larva and full grown adult.
This result is very significant. In the first place it is an important corroboration of the far-reaching theory of Adam Sedgwick as to the primitive history of the blastopore, with which it agrees in nearly every particular. To myself it was particularly interesting because it formed the final link in a chain of evidence as to what appears to me to be the true relation of larvae to each other and to adults. I have already indicated (University Circular No. 22), partially, the conclusions to which I have been led by the study of Thalassema, and this result in the case of Serpula, together with much other evidence which I have been able to collect, has led me to the formation of a new theory as to the relations of larvae, an account of which is to appear in the next number of the "Biological Studies." In brief it is as follows: As a simplest type of larva, and the most universal is found a form which agrees in essential respects with the young pilidium of Nemertians. It consists of a gastrula with a circumblastoporal band of differentiated tissue usually bearing cilia and with a tuft of cilia at the extremity opposite the blastopore mouth. It is in fact just such a gastrula as we have seen in Serpula. This type is found very widely distributed, being present in Coelenterata, Polyzoa, Brachiopoda, Vermes and Mollusks, and in a slightly modified form, i. e., without the circumblastoporal ring, in Echinoderms. This form is therefore taken as a starting point and a comparison is instituted between the methods by which this larva is developed into the full grown larva and the adult in the different forms. Leaving aside the Echinoderms, which for certain reasons are classed with the vertebrates and Balanoglossus, it is found that the above mentioned groups of animals are divided into two radically distinct classes. In the first class the body of the larva and the adult is formed by the elongation of that part of the gastrula body situated in front of the circumblastoporal ring, between it and the anterior ciliated tuft. The Coelenterata, Polyzoa, and Brachiopoda conform to this type. To produce the adult Coelenterata the larval type attaches itself by its anterior end, the body elongates, the circumblastoporal ring grows out into tentacles and the blastopore remains as the mouth. The Polyzoa have a like history, except that the two extremities of the blastopore are separated into mouth and anus. The Brachiopoda are a stiil more
In the second class the body of the larva and the adult is formed by the elongation of that part of the gastrula body situated behind or within the circumblastoporal ring. The Mollusks and Annelids and probably other
worms conform to this type. The development of Serpula as above described illustrates how this elongation takes place and an essentially similar history is found in other primitive Annelids (Thalassema and Polygordius). In Mollusks the same general change is seen, the body elongating in the same direction and the blastopore closing to form the ventral surface. In Mollusks, however, the ventral surface grows out to form the foot, the dorsal surface develops a shell, while the whole animal remains relatively short and the resulting form is very different from the Annelid, although they originally arise from the same larva by the same modification.
Gill in Neptunea. By H. L. OSBORN.
Some facts observed in studying the development of a species of Neptunea abundant at Beaufort, N. C., are of interest in connection with a study of the gastropod Gill which I presented in the Circular for July last. A brief recapitulation of the main features of the development will conduce to clearness. The head, foot and vela arise as ectodermal thickenings upon one end of the oval egg and soon upon one side, thereby designated as dorsal and opposite to the foot, the shell gland appears. The shell gland, at first a small ring, increases in size and its rims spreads over the yolk at the end opposite the head, vela and foot until it has covered half the egg, but the area immediately around the head, vela and foot is still unencroached upon. This area is in part the region of the future mantle, and just in front of the margin of the shell area it forms a thickened ridge. This mantle area is now broadly convex as though greatly bulged out upon the dorsal surface of the body. Upon its surface there appears a row of finger-like processes, these being mere folds or thickenings of the surface which form an interrupted ridge running antero-posteriorly upon the dorsal surface of the body. Later this dorsal surface begins to roll inward by an involution which begins near the head, and the mantle cavity is thus formed with the gill which has been carried along during the involution lying upon its roof. We have thus here the formation of a gastropod gill reduced to its simplest terms, namely, a series of dilatations upon the outer surface of the body. I do not know that it has ever been pointed out that the gills arise in any prosobranch before the mantle cavity is formed, but this mode of the formation of a mantle cavity is not unique, for Rabl has described much the same sort of thing in Planorbis. This mode of the formation of the prosobranch gill on the surface of the body and its infolding with the mantle cavity is flatly opposed to the conjecture of Spengel that the prosobranch gill is a ctenidium which has secondarily became fused with the wall of the mantle cavity, and bears out the view which I proposed in my previous paper.
Some Observations opposed to the Presence of a Parenchymatous or Intra-cellular Digestion in Salpa. By C. S. DOLLEY.
Dr. A. Korotneff has described (Zeit. f. Wiss. Zool., XL, 1, 1884) a huge amoeboid cell or plasmodium, which he figures as occupying the oesophagus and stomach of Salpa. He regards it as a rhizopod-like digestive organ, into the protoplasmic substance of which food is directly ingested, and he concludes that we have in Salpa (and in Anchinia) a true parenchymatous digestion, and he therefore questions the high genetic position of the Tuni
I have made a number of series of sections for the purpose of finding this body, and while it is true that these bear a very close resemblance to those figured by Korotneff, I feel confident that he has utterly mistaken their significance. I was able to trace the so-called plasmodium not only through the oesophagus and stomach, but also through the oesophagus into the branchial sac, and through the intestine into the cloaca, and have been able to show clearly that, instead of an amoeboid cell, it is actually the mucous excretion from the endostyle, with its entangled particles of food.
In studying a series of transverse sections of a Salpa which was well fed, we find, as we approach the oesophagus, a mass of material answering to the description and figures of Korotneff's rhizopod. It takes staining readily, and may be traced backwards into and through the oesophagus, stomach and intestine. As the sections approach the rectum, however, the mass gradually ceases to take staining, and is much more distinctly marked out from the