22 • HARLEY N. GOULD 



Figures 24 to 40 give successively the main steps of develop- 

 ment of the apyrene spermatozoon. As the spermatoblast in- 

 creases- in size (fig. 25) it becomes distinctly different from the 

 spermatogonium (fig. 24). Two centrioles (fig. 25, co) make 

 their appearance in the cytoplasm and very near them a large 

 capsidar body to which will be applied the somewhat unsatis- 

 factory term 'idiozome' (figs. 25 to 28, i). The proximity of this 

 body to the centrioles, and the strands which have sometimes 

 been seen reaching from it toward the centrioles, indicate that 

 the centrioles have come out of its interior. A few doubtful 

 cases have been seen where the centrioles seemed to be within 

 the idiozome. There are no lines radiating from it into the 

 cytoplasm as in the large 'centrosome' described by Reinke. 

 It arises suddenly and cannot be connected with a previously 

 existing centrosphere ; it disappears and leaves no trace behind. 

 During the spermatoblast stage the cytoplasmic granule referred 

 to above is also very prominent (figs. 25, 26, 27, x) but later can- 

 not be seen, or at least cannot be distinguished from chromatic 

 matter which has been throwTi free into the cell body from the 

 nucleus. 



The breaking up of the nucleus of the spermatoblast (figs. 26, 

 29, 30) and the division of the centrioles (figs. 27, 29, 31) consti- 

 tute the change to the 'spermatosome.' The nuclear membrane 

 dissolves and immediateh' the chromatic elements within the 

 nucleus form into ' karyomerites, ' or chromatic masses which 

 come to lie free in the cytoplasm (figs. 30, 31, ko) and become 

 scattered throughout the cell. The number, size and shape of 

 these bodies is variable. The smallest of them are no larger 

 than the chromosomes of the first maturation division of the 

 eupyrene series, and, like the latter, are short and thick, and 

 rather regular in shape. Others are much larger and very ir- 

 regular. The clumps of chromatin are often so large that all 

 the chromatic substance is contained in three or four of them. 

 It appears that in such cases parts of the nucleus become con- 

 stricted off and pass over directly into nuclear vesicles, i.e., 

 the several lobes of chromatic material (fig. 29) do not break 

 up into small karyomerites, but immediately form chromatic 



