STUDIES ON CHROMOSOMES. 235 



condition of the chromosomes of this particular cell, he has 

 unwittingly, and therefore without even subconscious bias, given 

 us what appears to be a beautiful example of a single curved or 

 U-shaped chromosome among a number of straight rod-like ones. 

 Unfortunately the cell is so cut that a few of the chromosomes 

 lie in another section so that the evidence is not absolutely 

 convincing although since nearly all of the chromosomes are 

 shown, it appears to be decidedly corroborative of my own 

 findings. 



PRIMARY SPERMATOCYTES. 



The later spermatogonia, in the resting condition, very com- 

 monly show two chromatin nucleolar-like bodies which, judging 

 from the fact that one or both often display a decided curvature, 

 are possibly to be identified with the two curved elements of the 

 division stage. In some cases the resemblance is decidedly 

 clear, in others less so. Sometimes the bodies appear to be 

 spherical or oblong rather than curved, but this appearance is 

 due in some instances at least to the position they occupy with 

 reference to the observer. Fig. 118 shows a group of such 

 spermatogonial nuclei as seen in a section of the testis. Parts of 

 the nucleolar-like bodies have been cut away in some but in the 

 nucleus below and to the left, one element is present in its en- 

 tirety and so oriented as to show its curvature. Later when 

 the growth period begins these bodies tend to fade out although 

 in such stages as Fig. 119 they are still visible. The disappear- 

 ance seems to be in the main a loss of staining capacity (Fig. 121) 

 rather than an actual dissolution. 



During the period of growth and development in which the 

 products of the spermatogonial divisions become primary 

 spermatocytes although important activities are obviously in 

 progress in the nucleus, I have been unable to determine sufficient 

 constancy in the details on which to base an adequate conclusion 

 regarding such important processes as synapsis. There is the 

 usual increase in nuclear size and with it characteristic appear- 

 ances at certain stages. For example, there is an apparently 

 early stage in which the nucleus seems to have the chromatin 

 material scattered through it in the form of a fine dust, with 

 occasional fine strands of linin and small fragments of chromatin 



