SPERMATOGENESIS OF LICE 665 



be described further here. The process is figured in Text-figs. 



A- J. 



We pointed out that the appearance of the mitochondrial 

 mass that we described was ascribed by Gatenby to faulty 

 fixation. This author favours the view rather, that the 

 apparently vacuolated mitosome is the result of faulty fixation 

 on the ' spireme ' type of mitosome that he describes in 

 Lepidoptera (5). In a recent paper of Bowen's (2), ' On the 

 structure of the " Nebenkern " in the insect spermatid ', there 

 is a re-sdew of the work on this subject, and from this it is clear 

 that the description given by practically all other workers, 

 besides the very exact account given by Bowen himself, agrees 

 closely with the development of the mitosome as we described 

 it in Pediculus. 



Apart from the fact that Gatenby's results have not been 

 confirmed by any other worker, there are several points in his 

 original description of the origin of the ' spireme ' mitosome 

 which make one cautious in accepting his views. He states 

 ' that the spireme is formed from the chromophile rim (outer 

 layer) of the mitochondrial body, wdiile the substance, in which 

 the spireme lies, is the coalesced inner substance (chromophobe 

 part) of the mitochondrial layer '. He gives three diagrammatic 

 figures illustrating the process by which this transformation 

 is brought about and these figures are certainly very misleading. 

 In the first one are drawn optical sections of spherical mito- 

 chondrial granules, in the other two these granules are shown 

 elongating and fusing together and apparently thus forming, 

 first of all loops, and finally a spireme. Now if two bodies 

 with a chromophilic outer layer and a chromophobic inner 

 substance coalesce, whether they are elongated or not, they 

 merely form a larger body of chromophobic inner substance 

 with a larger chromophilic outer layer. They do not form 

 a thread of chromophilic substance in a mass of chromophobic 

 substance, at least not by the mere act of coalescence, as 

 Gatenby's figure indicates. What these figures really show is 

 the lengthening of the optical sections of spheres, which are 

 of course circles, to form loops, and their joining together to 



