lOG L. DONCASTER. 



giving it a characteristic appearance (fig. 11). I'his becomes 

 converted into the head of the spermatozoon. 



It must be concluded therefore that in the male the normal 

 somatic number of chromosomes is eight ; that four " gemini " 

 appear in tlie prophase of the first maturation division^ and 

 that finally four chromosomes are distributed by lieterotype 

 and homotype divisions to each spermatid nucleus. 



Tliere is no trace of the '' polar body ^' formation described 

 by Meves in the spermatogenesis of the bee." 



Oogenesis. 



In the larva before it casts its skin within the cocoon the 

 ovaries are much like the testes of the male^ but larger, with 

 bigger nuclei. The ovary is enclosed in a cellular sheath, 

 and some ovarian cells are already larger than others ; these 

 will form the eggs, while the more numerous smaller cells 

 give rise to the nutritive and probably to the follicle-cells. 

 All the nuclei at this stage contain about eight chromatin 

 masses and one to three nucleoli (fig. 12). In the young 

 pupa the egg tubes are already differentiated, and in a 

 longitudinal section of a tube the changes in the nucleus can 

 easily be followed. At the apex of the tube the nuclei are 

 like those in the larval ovary ; below this zone the chromatin 

 becomes distributed through the nucleus as fine dots, which 

 are often aggregated together in one part, as in a sort of 

 synapsis (fig. 13). The egg nucleus then enlarges consider- 

 ably, and the chromatin appears as an irregular thread ; at 

 this stage two or three nucleoli are generally conspicuous 

 (fig. 14). After this stage yolk begins to be deposited, and 

 before the egg is ripe the nucleus, which has been very 

 large, dwindles so that in nearly ripe eggs I have been 

 totally unable to find it. 



In the larval ovary mitoses may be found in the ovarian 

 cells and in the sheath ; those actually in the ovary appear to 

 have eight chromosomes (fig. 15 a, h). But in the sheath in 

 - ' Auat. Anzeiger,' xxiv, 1903, p. 29, 



