230 BUMFUS. [Vol. V. 



that active division of the nuclei has been going on, and karyo- 

 kinetic figures are not uncommon. Not only have the nuclei 

 divided, but they have also approached the periphery and more 

 rapidly towards the flattened, the animal pole, than towards the 

 convex, vegetative pole. 



The division of the several nuclei is not contemporaneous, odd 

 numbers of nuclei resulting, but when division has taken place 

 about three times, from eight to twelve nuclei occupying the 

 egg, the animal pole begins to show some effects of the dis- 

 turbances going on below. Elevations and furrows appear 

 which are shown in PL XIV, Fig. C, and somewhat schemat- 

 ically on PI. XVI, Fig. 9, which represents a very thick trans- 

 verse section. The furrows are for the most part shallow and 

 not present on the opposite, vegetative, side of the egg. 



A meniscoid layer of fluid still extends over that portion of 

 the egg that is now seen to be the animal pole, though the 

 further stages of segmentation seem to bring about its oblit- 

 eration. 



Comparing these furrows with those observed in Atyephira, 

 I have not seen a rhythmic appearance and disappearance as 

 described by Ishikawa. Much variety is exhibited in the ar- 

 rangement of these blastomeres. In no case were there sugges- 

 tions of bilateral symmetry. 



The egg of Homarus, then, as Kingsley has clearly shown for 

 many other Crustacea, is primarily "ectolecithal," the cells divid- 

 ing independently of the yolk. Finally the egg becomes some- 

 what telolecithal, differing in this latter respect from the eggs 

 of many higher Crustacea so far as such have been observed. 



The yolk, as the dividing nuclei leave its centre, becomes 

 more granular, like that of the periphery, and there is no dif- 

 ferentiated central mass of any kind whatever. " Belated " cells 

 comparable with those found in Crangon by Kingsley ('87) were 

 not found in Homarus. 



The Morula Stage. 



A view of this stage is shown on PL XIV. The animal pole 

 is shown in Fig. D, while the vegetative pole of the same egg 

 is represented by Fig. E. The blastomeres of the former are 

 somewhat smaller than those of the latter, and at no time is 



