No. 2.] COMPARATIVE CYTOLOGICAL STUDIES. 409 



this peripheral part of the nucleus, which may be radially dis- 

 posed or else form a loose network. The size of the granules, 

 their abundance and staining intensity vary in different nuclei 

 of the same size, and there is no sharp distinction between the 

 smallest nucleoli and the largest of these granules. In this 

 species, as in the preceding, I was unable to detect any sub- 

 stance which stained like chromatin. 



I have been unable to determine the origin and ultimate fate 

 of these nucleoli, owing to lack of material ; but a few justifi- 

 able conclusions may be drawn from the facts at hand. Thus 

 the number and size of the nucleoli stand, as a rule, in a direct 

 ratio to the size of the nucleus. Further, those irregularly lobular 

 nucleoli described above probably represent amoeboid changes 

 of the nucleolus, such as have been seen in life by previous 

 investigators, though it is strange that these nucleoli differ from 

 all others in consisting of a single substance and in containing 

 no vacuoles. Lastly, the number and size of the vacuoles 

 increase, as a rule, with the size of the nucleus. 



It is worthy of mention that usually there are a larger num- 

 ber of very small nucleoli in the larger nuclei than there are 

 in the smaller nuclei, although the largest nucleoli of the 

 former are much larger than the largest nucleoli of the latter 

 nuclei. We must conclude, then, that though the size of the 

 nucleoli increases as a rule with that of the nucleus, new 

 nucleoli are also being formed as the nucleus grows larger. 

 Now some of these new small nucleoli found in the largest 

 nuclei have undoubtedly been produced by division from some 

 of the larger ones : thus I have frequently observed irregular 

 (amoeboid) nucleoli with oval prolongations, or with small 

 nucleoli closely apposed to their surfaces, and it probably is 

 correct to conclude that such small nucleoli are in process of 

 division from the larger ones (Figs. 23, 25, 27, 28, 33). 

 Whether all the small nucleoli of the larger nuclei have 

 had such a formation is difficult to determine, since in some 

 of the largest nuclei most of the smallest nucleoli may be 

 peripheral in position, close to the nuclear membrane, and 

 far removed from the larger nucleoli, so that it might seem 

 that the substance of these was extranuclcar in origin. The 



