Notes on the morphology of the Tunieata, 569 



The large blastomere, SI, has a very large nucleus, JV, and evenly 

 granular protoplasm which does not stain deeply with haematoxylin, 

 borax-caruline, or saftranin. Outside the blastomere is a mass of more 

 coarsely granular and deeply stainiug protoplasm in which no cell 

 walls can be discerned, but in which appear many nuclei all exactly 

 resembling the nuclei of the follicular epithelium. These have a de- 

 finite chromatic reticulum with rather large nodal swellings and no 

 nucleolus. 



Within the protoplasm of the blastomere as shown in this one 

 section are seven bodies similar in size to the follicle nuclei just 

 described, but quite difi'erent in appearance. I believe them to be in- 

 gested follicle nuclei. They do not stain so deeply as the nuclei 

 outside, though they are much darker than the protoplasm of the 

 blastomere in which they lie. We do not find in them the clear cut 

 chromatin reticulum with sharp contours such as we see in the follicle 

 nuclei, but in certain of them we do find Avhat appears to be such a 

 chromatic reticulum degenerating, because undergoing digestion. Ob- 

 serve especially the nucleus a. The reticulum is evident and I think 

 no one can doubt that the body is really a nucleus. Compared with 

 follicular nuclei the reticulum is seen to stain less deeply and the 

 fibrils and nodal masses do not have sharp contours. The whole ap- 

 pearance indicates the beginning of désintégration. I believe this 

 nucleus to have been ingested but a short time previous to the killing 

 of the embryo ^). At b and c are nuclei which have gone further in 

 the process of degeneration, the chromatin threads being more diffuse. 

 At d, e, f and g we see a further stage in the same process and at 

 Ä, j and h we observe within the ingested nuclei an almost evenly 

 granular mass of disintegrating chromosomes. In other blastomeres 

 and in another section of this same blastomere one can observe the 

 last step in the degeneration, a mere mass of debris no longer deli- 

 mited by a nuclear membrane from the surrounding protoplasm of the 

 blastomere. 



Notice that the less degenerated of these ingested nuclei lie on 

 the side nearer the periphery of the embryo. The inwandering follicle 



1) It is probable that fresh material killed and fixed promptly by 

 rapidly acting reagents will show newly ingested follicle cells in better 

 condition than would material allowed to stand sometime before being 

 preserved. In the latter case, the intra-cellular digestion of the follicle 

 cells might go one for sometime after the ingestion of follicle cells had 

 ceased, so that no newly ingested cells could be found. 



