322 ROBERT H. BOWEN. 



animation of the whole subject. The following abridged ac- 

 count has been drawn from Euschistus euschistoides. 



The earliest spermatogonia which I have studied are from the 

 cysts of large pyramidal cells arranged in a rosette, (see Mont- 

 gomery ('n), Fig. 3), and in these cells the mitochondria are 

 aggregated into a dense mass fitted closely to the nuclear mem- 

 brane like a cap. The position of the latter with reference to the 

 long axis of the cell is variable, and thus no constant polarity is 

 visible. From this point through to the diplotene stage the mito- 

 chondria are always thus massed together (Fig. i) except during 

 the spermatogonial divisions when they spread throughout the 

 cytoplasm in what appears to be a tangle of exceedingly delicate 

 threads and granules. Montgomery supposed the mitochondrial 

 cap to be an idiosome (idiozome), and he concluded naturally 

 that there were no mitochondria in the spermatogonia or at 

 least that they must be chemically different from those of later 

 stages. In this he was clearly misled by inadequate technique. 

 In point of fact, beginning at least with the rosette cells the mito- 

 chondria may be traced through to the mature sperm without a 

 break in continuity or any fundamental changes in staining 

 reaction. 



With the diplotene the spermatocytes begin to increase mark- 

 edly in size, and the cap of mitochondria likewise undergoes a 

 corresponding growth (Fig. 3). At the same time it grows looser 

 in texture and in the large cells is seen actually to consist of a 

 tangle of fine threads. As the growth period is entered upon, 

 the threads begin to migrate out into the general cytoplasm, and 

 in a short time become distributed uniformly throughout the cell 

 (Fig- 5). This movement is accompanied by an increase in the 

 diameter of the threads and probably in their length, but their 

 actual number seems to be little if at all affected. In the small 

 cell generations the breaking up of the cap is somewhat different 

 in detail, but the final result in all the cells is the same the mito- 

 chondria are distributed throughout the cytoplasm as a mass of 

 threads in what appears to be a hopeless tangle. This condition 

 continues throughout the growth period except in the large cells, 

 where the threads may undergo more or less extensive granula- 



