HAROLD H. PLOUGH. 



have already become aggregated into the definite spheroidal 

 nebenkerns, and the cytoplasm is clear and free from granules. 

 The chromatoid body, here unusually small, is seen in one of the 

 cells close to the wall of the nebenkern. 



It is unnecessary to give details of the metamorphosis of the 

 spermatids. In living material stained with janus green Lewis 

 and Robertson have shown that the nebenkern appears as a 

 mottled spherical mass, which finally divides into hemispheres, 

 between which the axial filament passes. These granular hemi- 

 spheres elongate as the tail draws out, eventually forming two 

 dotted lines, one on either side of the axial filament. Here again 

 the mitochondria appear as separate granules, with little tendency 

 to fusion even in the mature sperm tail. In a few preparations 

 stained by the Benda method I have noticed the "acrosome 

 sphere," described by Meves and by Montgomery at the opposite 

 side of a spermatid from the nebenkern (Fig. n). It stains 

 purple, which is the typical mitochondrial reaction. I have been 

 unable to trace its origin or subsequent history, but by analogy 

 with other forms it probably forms the perforatorium of the 

 mature sperm. Since the chromatoid body never divides it 

 should be found in one fourth of the spermatids. In order to 

 test this expectation ten cysts of spermatids in various stages 

 were selected at random from several preparations, and the 

 total number of cells and chromatoid bodies recorded. The 

 results follow : 



No. of Cyst. No. of Spermatid Nucle'. No. of Chromatoid Nuclei. 



1 59 12 



2 78 21 



3 56 15 



4 54 ii 

 ' 5 64 13 



6 40 9 



7 50 ii 



8 101 22 



9 61 15 

 io 56 14 



Total 619 143 



The 143 chromatoid bodies observed are fairly close to the 

 expected number 155. 



With the elongation of the spermatid the chromatoid body 



