bb KANSAS UNIVERSITY QUARTERLY. 



fluence from the rest of the chromatin. Studies in progress in this 

 laboratory by a student, Mr. W. 8. Sutton, show that so strenuous is 

 this endeavor, that during all the spennatogonial divisions the ac- 

 cessory chromosome is provided with a separate vesicle whose con- 

 tents do not mingle with those of the ordinary nuclear vesicle, except 

 during the actual process of separating the daughter chromosomes. 

 Such a refinement of nicety would, to say the least, be extremely in- 

 compatible with our usual ideas of degeneration. Some more im- 

 mediate connection with the idioplasm than is enjoyed by the ordinary 

 chromosome, it seems to me, would be a more probable explanation 

 of the accessory chromosome's behavior than would one which regards 

 it as possessing the evidence of degeneration. 



In respect to the function of this remarkable element, nothing 

 definite can as yet be said. By its formation, it is removed from the 

 influences operating upon the rest of the chromatic material during 

 the long-continued prophases of the first spermatocyte division. This 

 is the time when the fundamental differences in chromosome struc- 

 ture between the germ cells and the somatic cells are inaugurated, 

 and during this time the accessory chromosome remains apart and 

 distinct from the rest of the chromalic material. It thus seems to be 

 the conserver and bearer of certain properties which it is desirable 

 not to have disturbed during the early phases of the first s])ermato- 

 cyte division. The pan it plays in fertilization has not yet been de- 

 termined, and so we have no definite ground upon which to base any 

 theories concerning its function. 



There is one thing, however, which I think stands out clearly and 

 definitely as a result of even our limited knowledge of this element. 

 The theory of the individuality of the chromosome must certainly re- 

 ceive a strong sujjport from the behavior of this aberrant representa- 

 tive. Indeed, a more conclusive proof could hardly be imagined. 



Concerning the name to be applied to this element, perhaps a little 

 might be said. I am more firmly than ever convinced that it should 

 be classed among the chromosomes, since it really is one and never 

 anything else. Under no consileration, I believe, should it be placed 

 with the ill-defined group of nuclear bodies included under the term 

 "nucleoli."' The real character of the chromosome cannot be ascer- 

 tained until its office during fertilization and cleavage has been 

 discovered; meanwhile the qualifying term "accessory" serves to 

 distinguish this chromosome from all others, and is general enough 

 not to predispose any one toward one conception or aiiother while the 

 solution of its character is in abeyance. The strictly chromatic nature 

 of this element is recognized by Paulmier in his latt^st work (26), 

 where he designates it as the "small chromosome.'' It is to be re- 



