SPERMATOGENES1S OF SCUTIGERA FORCEPS. 163 



large as before (Fig. 8, g, /i, /, /). On close inspection, however, 

 it may be seen that the vacuoles have greatly increased in size. 

 Often these become united, and form one large vacuole at the 

 center of the karyosphere, around which lie the remaining masses 

 of chromatin (Fig. 8, g, /i, /). When finally all these have 

 emerged, there is left a mass of material staining more or less 

 darkly, probably a truenucleolar portion of the karyosphere, and 

 one small, round, dense black body, the accessory chromosome 

 (Fig. 8, /). This latter presents exactly the same appearance as 

 when last seen during the telophase, except for a slight increase 

 in size, which may readily be referred to natural growth. The 

 remaining mass, or true nucleolar portion of the karyosphere 

 (fig. 8,y ), now breaks up into small round bodies of more or less 

 irregular size, which soon become indistinguishable from the re- 

 mains of the metaplasm still lying in the nucleus during the 

 growth period (Fig. 12, 13, 14). For this reason it is impossible 

 to determine the ultimate fate of these bodies ; for all seem to be 

 of about the same size and appear to take the stain equally well. 



Immediately after leaving the karyosphere, the chromosomes, 

 as was shown above, shorten into dense granular cords (Fig. 9). 

 These now undergo a longitudinal cleavage (Fig. 10), and the 

 double thread of chromatin breaks up into a number of short 

 portions of irregular size (Fig. 11). Whenever the position of 

 these made counting possible, the uniform number of six in each 

 half was to be observed. 



Until the opening of the active prophase, the nucleus appears 

 very clear, much more so than the cytoplasm, and contains a 

 finely granular and irregular linin net- work, the meshes of which 

 are much coarser than those of the cytoplasm. Metaplasm 

 bodies left over from the preceding growth period may occasion- 

 ally be seen caught in the meshes of this net-work, but with 

 the exception of these and the karyosphere, no other structures 

 are visible within the nucleus. Just preceding the emerging of 

 the chromosomes from the karyosphere, however, the nuclear 

 area becomes clouded over here and there with very thin, diffuse 

 masses in which the segments of chromatin seems to become en- 

 tangled as they pass out into the nucleus. It is these masses of 

 achromatic matter which Bouin (Lithobius forficatus), Bouin an J 



