5O McCLUNG. 



greater size and deeper color. Then it comes to lie in the vacuole 

 of the nucleus. At length, what I consider its remains are found 

 for some time faintly discernible in the chromatic mass of the 

 head of the immature spermatozoon. In later stages this body 

 is not to be distinguished from the rest of the chromatic mass. 

 I was at first inclined to believe that this body allied itself with 

 the centrosome to help in forming the neck-body, but was soon 

 convinced that this is not true, because I observed that the two 

 parts of the centrosome and this problematical body exist at the 

 same time in the same spermatid. In Figs. 90, 92, and 106 the 

 body in question is seen in contact with the chromatic mass, and 

 in Figs. 103, 104, it is nearly included in the chromatic cres- 

 cent. Later, as already indicated, it becomes indistinguishable 

 from the rest of the head of the spermatozoon. Accordingly, I 

 am unable to determine whether or not it forms any definitely 

 limited portion of the head." 



24. While Henking was the first to discover the unusual be- 

 havior of a " nucleolus " in the spermatocyte which, in all of its 

 manifestations but one, corresponds to an ordinary chromosome, 

 Montgomery ('98) deserves the credit for observing that this 

 body is merely a chromosome of the spermatogonia that pursues 

 a somewhat different course from the others. Unfortunately, 

 however, his interest in nucleolar structure led him to denomi- 

 nate it, with Henking, a nucleolus and it is accordingly under the 

 name " chromatin nucleolus" that we shall trace its history 

 through the spermatocytes of Euc/iistns. 



25. The persistence of a color reaction in this element that is 

 characteristic of chromosomes in the metaphase first attracts 

 Montgomery's attention. He states in regard to this that " in 

 each nucleus, from the commencement of the anaphase on, one 

 of the chromosomes still retains the red stain characteristic of all 

 of them in the immediately preceding period, and this particular 

 element is destined to become the chromatin-nucleolus, the meta- 

 morphosis of which will be described later." 



26. Subsequently he discusses the chromatin nucleolus at 

 some length and from this part of his paper I will quote passages 

 bearing upon its name, staining reaction, form, behavior, final dis- 

 position, and function. He says : 



