194 KINGSLEY AND CONN 



mediary layer contains a large proportion of protoplasm is shown by the free cell forma- 

 tion which subsequently occurs in it, to be described farther on. 



It has been impossible to give any adequate representation of these amoeboid move- 

 ments as they utterly surpass any efforts of the artist, but figs. 15 and 17 may serve 

 to convey some slight idea of the appearances. Both are taken from blastoderms of eight 

 cells. In fig. 17 only two cells are shown, each of which is about to segment while two 

 processes are shown arising from one cell and uniting with the protoplasm of its neighbor. 

 In this case the union was not broken until after the segmentation was completed. The 

 other (fig. 13) represents an entire blastoderm of eight cells after the segmentation 

 furrows are complete but before the reappearance of the nuclei. 



At the time of the reappearance of the nuclei in the blastoderm of four cells, grooves 

 were noticed extending down from the blastoderm a short distance on the surface of the 

 yolk (fig. 14) ; but they soon faded out, not lasting over four or five seconds. This 

 phenomenon was noticed at two subsequent stages ; once when the blastoderm was composed 

 of sixteen and once when of about sixty blastomeres. It may have occurred at other times 

 but was not looked for ; in fact the times when it was seen were the result of accident, 

 it being incidentally noticed while other changes were being watched. 



Concerning the internal features of the segmentation we regret that we can say nothing. 

 Many times the nuclei of the blastoderm were carefully watched, but all that can be said is 

 that they gradually faded away from the sight, growing less and less distinct until at last 

 they were invisible and had utterly disappeared before the segmentation of the protoplasm 

 began. After the cells had divided the nuclei again became visible but rather more 

 rapidly than they had disappeared. In this disappearance and reappearance there did not 

 appear to be any change in the size of the nuclei, but rather their optical properties more 

 and more approximated that of the surrounding protoplasm until at last the microscope 

 was unable to differentiate them. At no time while the segmentation fissures were being 

 formed were the nuclei to be seen. In vain we looked for those interesting features con- 

 nected with cell division which have been described in such detail by Butschli, Flemming, 

 Klein, Peremeschko, Schleicher, Strasburger and others. Except in the case of the 

 maturation of the egg of Merlucius described above, we have but twice seen anything in 

 the eggs of Teleosts which in any way even approximated an aster, am,2)hiaster or " spin- 

 del-kern "} Once asters were seen in a large proportion of the cells of a blastoderm com- 

 posed of about one hundred segments. The other time a single aster was seen among 

 the free yolk nuclei or rather, as I prefer to call them, the free nuclei of the intermediary 

 layer. In both cases circumstances were such as to prevent any detailed observations 

 upon them, while the little which was seen is of no value standing by itself and hence is 

 not described. It is sufficient to say upon this point of internal features of segmentation 

 that in the earlier stages of division nothing comparable to the phenomena I have seen in 

 the eggs of other forms could be distinguished without the aid of reagents, which however 

 do not readily penetrate the envelope of the eggs which are studied. The eggs of Mer- 

 lucius afford in this respect a striking contrast, as in them Mr. Van Vleck obtained by 

 staining well marked spindel-kerne. 



1 The studies of 1882 require the modification of this state- though they did not stain with the more common reagents, 

 ment for I was able several times to see these structures, they The appearance of both asters (b) and spindelkern or amphi- 

 being well stained by a solution of carmine in acetic acid asters (x) sre shown in pi. 15, fig. 24*. 



