THE MITOCHONDRIA AND OTHER STRUCTURES. IO7 



manner as did those of the apical cell. This striking resemblance 

 of the apical cell to the somatic cells in contrast to the germ cells 

 suggests the possibility that the apical cell may be more closely 

 related to the somatic cells than to the germ cells. 



Primary Spermatogonia. In the primray spermatogonia both 

 the mitochondria and the neutral red granules can be identified 

 in the unstained cell. In the resting cell the mitochondria appear 

 as delicate granular threads and at this time these threads seem 

 to radiate from the distal pole of the cell (i. e., the region of the 

 last connection with its sister cell at mitosis). The mitochondria 

 of the primary spermatogonia stain less intensely with Janus 

 green than does that of cells in a later stage of development and 

 when stained with Janus green the delicate threads become rapidly 

 distorted and appear as granules. The neutral red granules, 

 from 4 to i o or 12 in number, are larger, more or less round and 

 much more refractive than the mitochondria granules. These 

 neutral red granules, so far as was seen, did not seem to be located 

 in any definite region of the cell, but were scattered through the 

 cytoplasm. 



Secondary Spermatogonia (Period of Multiplication). The 

 secondary spermatogonial cells are smaller than the primary 

 spermatogonia and the mitochondria are usually in the form 

 of fine, granular threads scattered from the distal end of the 

 cell towards the nucleus. As the cell approaches the resting 

 condition the mitochondria become more uniformly scattered 

 throughout the cytoplasm. In a few observations the mito- 

 chondria appeared to be absent from a region at the extreme 

 distal pole of the cell, possibly the mitosome (i. e., the remains of 

 the spindle, Figs. 2, 4, 6). 



During mitosis the mitochondria arrange themselves as long 

 threads close to the spindle and frequently they have the ap- 

 pearance of abnormally thick spindle threads. During the con- 

 striction of the cytoplasm at late anaphase the mitochondria 

 threads again become granular and at telophase the mitochondria 

 are separated into two practically equal amounts, one of which 

 passes into each daughter cell and from this mass the mitochon- 

 dria migrate towards and partly around the nucleus (Fig. 4), 

 as can be seen in the first spermatocyte. 



