VARIATIONS IN THE SIZE OF CHROMOSOMES. 22Q 



One slide which had most of the stain removed contained a 

 number of cells of the early prophase with only one group of 

 granules showing distinctly. The other granules were either 

 very faint or else did not show at all. The granules of this 

 group varied in size and number and in many cases were in the 

 process of division (Figs. 69, 70, and 75 to 80). When the cells 

 grew older, as could be determined by the increase in size of the 

 cell and the appearance of the spiremes of the other chromosomes, 

 the granules of this group began to come closer together and 

 finally fuse (see Figs. 71 to 74 and 82). 



The body produced by this fusion is unquestionably a chromo- 

 some because it is made up of granules which have the power of 

 division. It is not the accessory chromosome for the accessory 

 is present in practically every cell containing it. 



The chromosome appearing in this series of observations seems 

 to vary in size as commonly found among corresponding chromo- 

 somes of the same individuals (described above) (compare Figs. 

 73 and 74). 



The number of granules in each group where no fusion had 

 commenced \vas as follows: 7, 9, 9, 14, 9, 10, 8, 9, II, 10 between 

 9 and 10 seemed to be the average. The fact that some granules 

 had not divided could account to a certain extent for the dif- 

 ferences in number, but not in every case, as Fig. 70, in which 

 but one granule is undivided would give but 10 granules if this 

 were divided. An examination of the other groups will show 

 like discrepancies. Therefore the number of granules varies 

 independently of their condition of division. 



The variation in the size of the granules in cases where fusion 

 had not occurred, was considerable. Even where all of the 

 granules had divided they varied in size (see Fig. 75, as well as 

 many of the other groups figured). This is true whether we 

 compare granules of the same cell or of different cells (see Figs, 

 following 68 and 75). 



(6) Unequal Division. In some of the lateral views of the 

 first spermatocyte a few small chromosomes were found dividing 

 unequally (Figs. 85 to 91). One cell contained two chromosomes 

 dividing unequally (Fig. 88). Small chromosomes were found 

 dividing unequally in the second spermatocyte (Figs. 83 and 84). 



