190 KIXGSLEY AND CONN" 



slight difference in time being noticeable with a change in the temperature. The yolk sac 

 has rapidly decreased in size. 



X. The formation of the mouth, the complete disappearance of the yolk sac and the 

 deposition of pigment in the eye. 



Though the processes above outlined and now to be described present many striking 

 differences from those which are found in fresh water fishes,. the} r are essentially similar, not 

 only in all the eggs of the marine forms which we have studied, buttliey also present many 

 resemblances to those of other marine forms as described by Van Beneden, Haeckel, 

 Kupffer and others, though seeming to indicate- that there are two distinct types of 

 teleost development, one for the fresh and the other for the salt water forms. However, 

 we are not yet possessed of sufficient material on which to base any generalizations, since 

 we know less about the development of the Teleosts than of any other Vertebrate type 

 with the exception of some of the lower groups of the old class of fishes. 



The description which we give is purposely detailed and may be even prolix, and for 

 these reasons : but few forms of marine fishes have been studied and so detailed observa- 

 tions are necessary to serve as a basis for future comparison; the second is that our paper 

 may be of more aid to American students who as a rule have no such facilities for consult- 

 ing books as have their co-workers in the old world. Besides the works of Alexander 

 Agassiz, Drs. Brooks, Garlick, Lockwood, Putnam, Ryder, and Wyman, referred to in the 

 bibliography, I do not know of a single paper by an American on the embryology of the 

 Teleosts, while all papers embracing any original investigation on the embryology of the 

 other Vertebrates will not exceed- two dozen and of these fully one-half were not at their 

 time of publication any contribution to knowledge. With such a poor showing surely any- 

 thing which may incite to better work may be pardoned. 



I. Maturation of the Ovum. 



We were unable to make any observations on the maturation of the eggs which we 

 studied, 1 nor to witness the phenomena connected with the impregnation, but the following 



1 During the summer of 18S2 eggs were taken from the liv- this operation does not include all of the protoplasmic portion 

 ing eunner some being fertilized and others not, and from of the egg, a thin layer (exaggerated in the figures) extend- 

 the study of the latter I am able to add a little to the account ing down over the yolk and in all probibillty giving rise to 

 of the maturation of the egg and to say a word concerning the the intermediary layer. While this segregation of the pro- 

 formation of the polar globule in addition to the statements toplasm is taking place the aster appears, followed by the 

 of the previous year. I woidd, however, state that it is barely formation of the polar globule. This aster appeared, each 

 possible that tlie supposed unfertilized eggs were in reality time it was seen, as a true aster, not an amphiaster, but this 

 fertilized, as, for obvious reasons, I cannot say that there were may be the result of the position of the egg, for were an 

 no spermatozoa in the water in which they were kept. These amphiaster viewed in the direction of the axis it would pre- 

 eggs in general appearance have been described at the begin- sent this appearance. At the centre of the aster there 

 nin'4 of the second section of this article, and hence the appeared the polar globule in a manner almost exactly simi- 

 description need not be repeated here. The features of lar to that so often described in the eggs of invertebrates, 

 maturation witnessed were a disappearance of the nucleus Once on rotating the egg the polar globule was actually 

 and of the strongly refractive globules; then the protoplasm witnessed in its passage through the mieropyle as shown in 

 began gathering itself together as shown in the figures 9, 10 figures C and 7, its connection with the egg being completely 

 and 11. A slight constriction appears around the central por- severed. At another time I saw a projection which I am 

 tion of the protoplasm which, cutting down and then in, sepa- inclined to regard as a polar globule attached to one of -the 

 rates the germinal portion of the egg from the yolk giving resulting cells of the first segmentation (fig. 8, p-g), but as 

 it eventually the shape of a button. It is to be noted that the process of formation was not witnessed I am not positive 



