Notice of Observations on the Developement of the Seminal Fluid and Organs of Generation in the Crustacea. By HARRY D. S. GOODSIR, Conservator of the Museum of the Royal College of Surgeons in Edinburgh.* Communicated by the Author. Shortly before the male Crustacean comes into season, the generative system is observed to change its appearance very considerably, so as to assume a very different aspect from that which it generally bears. This change is first observed in the testicle itself, which, when inactive, is almost altogether lost in the folds of the liver. The first change which takes place is in the size of the gland, which is produced by means of the germinal cells,† in each acinus of the gland becoming active, secreting, and filled with small nucleated cells; this secretion goes on until the germinal cell is quite full, when it bursts and empties itself into the cavity of the acinus. After these small nucleated cells, or, as we shall now term them, "secondary cells," have lain in the cavity of the acinus for some time, they also begin to take on an active character as secretive cells, and become in their course downwards towards the vas deferens very much larger and at the sametime filled with young cells. We shall now then follow them in their course from the acinus down to the vas deferens. In the acinus we find the greater number merely increased slightly in size, a considerable number, however, already contain two, three, four, or more cells, and a few are even as large as those found in the epididymis. As we descend and examine the contents of the epididymis, which appears in this class of animals to be a kind of receptacle for the proper elimination of these cells, instead of finding a great number of simple nucleated cells, we find it containing, with very few exceptions, parent cells, large, and distended with young ones. We still, however, find a few of these parent cells with only one, two, or more young within them, and others still in the same state as when they left the acinus, from which they had originally been secreted. On descending still farther, and examining the contents of the vas deferens, we will find that these parent cells are all large and distended with young, and some of them even burst, with the young lying scattered around about the empty cell. These cells, however, which burst in the vas deferens are precocious, although we find examples of it taking place in the epi * Being an abstract of Part I. of Crustacealogical Researches, preparing for publication. On the Ultimate Secreting Structure, and on the Laws of its Functions. By Mr John Goodsir. In the Transac. of the Royal Soc. of Edinburgh, vol. xv. Part ii. didymis, and even higher up the gland, for in general all these parent or secondary cells are thrown into the spermatheca of the female before they burst. Preparations, however, for this destruction of the parent cell seem to be going on in the vas deferens of the male a long time even before the testicle has arrived at its maximum state of periodic developement, for the difference between the cells in the epididymis and vas deferens is quite apparent. Those in the former are quite full of young cells, the walls of the parent cell lying tightly and closely upon, and binding them together as it were; whereas those in the latter, although quite distended, are not full altogether of cells, but with a fluid which appears to separate the young contained cells from one another, and from the walls of the parent cell. If a female crab can be procured shortly before spawning, the spermatheca will be found quite full of these young cells, which we shall henceforth term primary, or spermatozoal cells, with a few parent or secondary cells floating amongst them. If the crab is still farther advanced, we will find that these secondary cells have disappeared altogether. These cells in the spermatheca are suspended in a thick albuminous fluid of a milky colour. Throughout the whole course of the testicle and epididymis, we find floating in a thick glairy fluid, along with the cells, in masses of an irregular-shaped, clear-looking appearance, a substance which apparently forms the nutriment of the cells, for this substance is always found in greatest quantities high up the organ, where the secondary cells are in an active state of growth and secretion, and of course requiring a supply of nourishment; whereas in the vas deferens, after the cells have arrived to a state of maturity, little or none of this substance is found. How this substance is secreted, or in what part of the organ, I have not yet been able to ascertain. The above description of the secretion and developement of the seminal fluid refers to all the Crustacea. It will be found, however, that this fluid varies more or less in its character in almost each species. In the May and June Nos. of the Ann. des Sc. Nat., a translation of a paper will be found, "On the Seminal Fluid of the Crustacea and Cirripeda; by M. Kolliker of Zurich. That gentleman, in the above paper, looks upon the filiform bodies which are found in such numbers generally in the interior of the testicle of the lower crustacea, as the spermatozoa. Now, as far as my observations have gone, it appears to me that these are parasitic entozoa (Filaria). My observations had been directed to these animals sometime before I had seen M. Kolliker's paper, at which time I had made up my mind as to their parasitic character, and for the following reasons: From observations on the origin and developement of the spermatozoa in the higher Crustacea, it had been made out that these were developed from cells, and from cells only. Now in every instance these Filaria were always found to be the same, never changing their characters in the slightest degree. Besides, the developement of the seminal cells in these lower Crustacea, was always going on in the same way as it did in the higher, and with out any appearance in the primary cells of the enclosed bodies, being like these Filaria. This, of course, also extends to M. Kolliker's observations on the same fluid in Cirripeds, for they must be looked upon now as Crustaceans also.* As the ova pass through the spermatheca, they come in contact with the spermatozoa, and in this way are impregnated. They also appear to obtain in this organ a thick coating of albumen, which afterwards becomes the ovisac. The organs employed in this class of animals for the proper defence of the ova, after they have been excluded from the ovaries, and during the time they are attached externally to the mother, are very interesting. After a careful analysis, they will be found throughout the whole class to be either legs not fully developed, or parts of these organs very much developed. The first of these divisions will be found to exist in the higher Crustacea, such as those belonging to the Brachyura, the Anomoura, and Macroura; this form is also found in the Araneiformes. It is in the Stomapoda we first observe these organs assuming another character, namely, that of protecting scales. We find this character gradually making its appearance, however, in the lower Macroura, as in Hippolyte and Palemon, where we find the ova attached by means of filaments to broad scales, and in the other genera; if this is not present, the usual armature of the body will be observed enormously developed, so as in some cases almost to meet, by means of their edges, on the abdominal surface of the body. In the Amphipoda, Læmodipoda, and Isopoda, we find these ovigerous scales bearing a considerable resemblance to those of the Stomapoda. In the Branchiopoda this character still exists, but in rather a more interesting form. In Apus we find the ova contained in a cavity formed by the expansion of the first joint of the eleventh pair of legs into two large circular-shaped and hollow plates, which, when closed together, form a safe means of defence. Through the genera Branchipus, Artemia, &c., we are led to Daphnia, Polyphemus, and Evadne, where we find this means of defence in its maximum state of developement, namely, one, or perhaps more, pairs of legs enormously developed, so as not to cover the ova only, but the whole body. The occurrence of this in these animals, is the cause of their unusual and grotesque appearance. From this form we are more suddenly brought through Saphirina and Cetochilus to the Monoculi, where we find a different means of defence altogether. Instead of great developement of the feet, we find one pair, or perhaps more, of these organs aborted altogether, and sacs or bladders are secreted each time the animal becomes loaded with spawn. This form is carried into, and continued throughout all the Siphonostoma, until we reach the Araneiformes, where we again find these organs assume almost the same appearance as those with which we first * Edinburgh New Philosophical Journal for July 1843. Vol. 35, p. 88. |