insect spermatogenesis 601 



The Formation of the Sperm, 



The Structure and Fate of the Mitochondrial 

 Body or Nebenkern, 



The condensation of the mitochondrial vesicles to form the 

 nebenkern (macromitosome of Gatenby) in Callosamia 

 follows immediately upon the completion of the second sperma- 

 tocyte division (fig. 43). For a detailed study of the method 

 of this condensation the Lepidoptera offer the best material 

 which has yet been found, the individual chondriosomes being 

 so large and their constituent parts so clearly differentiated 

 that the progress of events is not obscured by the stain, as 

 in the case of the Hemiptera (cf. Bo wen, 19226). Gatenby 

 (1917 ft) has given a series of figures showing the various steps 

 in the process, and up to the stage shown in his figs. 15 and 38 

 the appearances in Callosamia are so nearly identical that 

 additional figures seem unnecessary. According to this worker 

 the process of condensation consists of a flowing together 

 of the mitochondrial bodies, ' forming at first elongated 

 structures, then loops, and finally filaments, the latter joining 

 up gradually to form a tangled anastomosing figure ', and 

 finally, ' a perfectly coiled spireme '. With this interpretation 

 of the process of condensation I am inchned to disagree, and 

 would like to suggest an alternative explanation which, I 

 believe, is also more in harmony with the later condition 

 of the nebenkern. 



I agree with Gatenby that the essential feature in the 

 condensation phenomena is the flowing together or fusion of 

 the mitochondrial vesicles. But, as I interpret it, this results 

 not in forming loops or threads but merelj^ larger aggregates of 

 chromophobic materioJ, the chromophilic material running 

 together to form more or less complete partitions between the 

 chromophobic droplets. Simultaneously the chromophilic 

 material is withdrawn from the periphery of the mass as 

 a whole, so that finally a spheroid of chromophobic material 

 remains, subdivided in an irregular manner by chromophilic 

 partitions. One might, indeed, liken the whole nebenkern to 



