75G NATURAL HISTORY OF AQUATIC ANIMALS. 



a trace of the connective tissue in which the rudiments of the latter are usually imbedded 

 remained, but the hepatic follicles or ultimate saccules of the liver were lying in immediate 

 contact with the mantle, with no tissue whatever intervening. 1 have hitherto found the liver 

 surrounded by a thick stratum of connective tissue in all of the specimens examined. The state- 

 ments in a previous portion of this essay in regard to the existence of vessels which traverse this 

 connective tissue mass will therefore have to be modified so far as to say that not only does the 

 connective tissue of the body mass completely disappear, but also the vessels themselves which 

 are excavated through its substance. 



Turning now to the condition of the mantle, I find this in a no less remarkable state than the 

 parts already described. The " vesicular connective tissue cell*," as they have appeared to me 

 hitherto, have given place to an entirely different structure, apparently much less solid and 

 substantial. Instead of the clearly defined coarsely cellular structure usually noticed in sections 

 made from less impoverished individuals, the tissue has now become very coarsely areolar, all trace 

 of the peculiar nuclear bodies having vanished, together with the internal protoplasmic network 

 which they so clearly exhibit. The areolae inclosed by the fibers of the connective tissue of the 

 mantle are very coarse and may measure as much as half a millimeter across in sections of the 

 hardened and shrunken specimen. When the mant'e was gorged in life, with blood probably, some 

 idea of the coarseness of these meshes may be formed. The meshes may then have measured four 

 or five millimeters in diameter, the resulting cavernous state of this highly elastic tissue enabling 

 the mantle to become gorged or swollen by endosmosis to a remarkable degree, so much so as to 

 cause the animal to be apparently bulky, yet in reality distended with sanious fluids merely. The 

 question now arises, What has become of this connective tissue which has so completely disap- 

 peared f The only interpretation which I can offer is that the connective tissue substance has 

 been transformed into sexual products which have been poured out by way of the efferent sexual 

 ducts, and ihat our specimen represents the extreme of exhaustion consequent upon the completed 

 exercise of the reproductive function for the season. The animal, in other words, has now exhausted 

 ite germ-producing resources, and must begin to feed and store up material for the next season's 

 generative products. It therefore becomes highly probable that the reproductive organs develop 

 anew each season. My reason for thinking so is, that in this specimen the atrophy or wasting 

 away of the reproductive organ has gone so far that no trace even of the efferent ducts of that body 

 remains. The specimen, taken as it was in July, also shows that the spawning season may be 

 completed before the end of summer. 



The connective tissue of the Oyster is, therefore, in reality transformed into ova and sperma- 

 tosoa, depending simply upon the sex of the individual whether it shall be the former or the latter. 

 This also raises the question whether the same individual may not be of a different sex during 

 different seasons, since it appears that the whole reproductive organ disappears and develops anew 

 every year. This it is however to be noted is arguing from a very different basis from that of 

 some foreign writers who have been absurdly illogical enough to say that the Oyster was of a 

 -different sex in different years, apparently forgetting that it would be impossible to open the same 

 individual twice in succession; since opening it kills the animal and puts the second examination 

 totally out of the question. 



The function of the mesenchymal or connective tissue in the Oyster is, therefore, of the nature 

 of a store of reserved material protoplasm laid up for the purpose of conversion into germs as the 

 reproductive organ develops anew. It is then in the highest degree improbable that it is of the 

 nature of an oily or fatty substance, out of which it would be impossible to form such highly vitalized 

 bodies as the ova and spermatozoa of the Oyster. While it is true that we find the mesenchymo 



