SPERMATOGENESIS OF LICE 663 



the same name, we suspect that it belongs to the Golgi 

 apparatus. Attempts to prove this by Kopsch's method . . . 

 have, however, failed to confirm this behef. . . .' We took this 

 view that the body with which we were dealing was probably 

 the ' acroblast ' on account of its behaviour in moving ulti- 

 mately towards the tip of the developing spermatozoon, and 

 we associated it with the Golgi apparatus because we were 

 convinced that the ' acroblasts ' of Gatenby were really the 

 Golgi bodies of earlier writers — a conclusion at which Gatenby 

 ultimately arrived — not in the paper on Smerinthus quoted by 

 Gatenby and Woodger, in which no mention is made of 

 the Golgi apparatus, but in a paper published two years 

 later (7). 



In the three species of lice examined there is, in each case, 

 a conspicuous body which corresponds to the ' acroblast ' of 

 Pediculus, In the horse-louse its history could be made out 

 most clearly. It first appears just prior to the prophase of the 

 spermatocyte division (Text-fig. d). In Pediculus we stated 

 that the ' acroblast ' may sometimes be double at the time 

 of its first appearance, but is always a single spherical body 

 later. In the horse-louse it is usually, but not always, double, 

 and remains so until the spermatid has formed and is elongated. 

 Its appearance is very striking and its shape somewhat difficult 

 to describe. Its two parts are sometimes equal (Text-fig. h), 

 but more usually one is smaller than the other (Text -fig. d and 

 j). The shape of each half may best be described as ' bun- 

 shaped ". They are placed with their flat sides together but 

 are never touching. They are always separated somehow by 

 a transparent acromatic layer. Sometimes the two halves 

 are seen to be comparatively far apart (Text-fig. f and j). 

 If the difference in size between the two halves is great the 

 smaller half is almost spherical. In the elongated spermatid 

 just before the nucleolus finally disappears the acroblast is 

 a single body (Text-fig. k) placed against the nucleus close to 

 the double centrosome, as in Pediculus. It thus looks highly 

 probable that during spermateleosis the double acroblast loses 

 one of its halves, which passes away from the nucleus and 



