SPERMATOGENESIS OF SCUTIGERA FORCEPS. l6l 



Another noteworthy feature characteristic of this period is the 

 presence of metaplasm in variable amounts within the nucleus. 

 Immediately after the reconstruction of the nuclear membrane, 

 when the dense mass of chromatin is beginning to become more 

 diffuse, so that the presence of foreign matter could easily be de- 

 tected, the nucleus never contains more than the one small round 

 body, the accessory chromosome, beside the mass of thread-like 

 chromosomes. But as the cell increases in size, others gradually 

 appear in the nucleus, and less frequently in the cytoplasm. 

 These bodies are homogeneous, and, like the karyosphere, take 

 a dense black stain with the iron hsematoxylin. In number they 

 vary widely, some cells being apparently entirely free of them, 

 others containing them in large numbers ; while in size they 

 range from scarcely distinguishable particles to large spheres. 

 These bodies seem to be largest and most numerous during the 

 mid-growth period. As the 'prophase approaches, they seem to 

 decrease in size, and by the time the karyosphere breaks up, their 

 remnants appear as mere particles scattered through the nucleus. 

 Those found in the cytoplasm persist about the same length of 

 time, although there thev are much less common than in the 



o > 



nucleus. These bodies present in both nucleus and cytoplasm, 

 correspond to the " ergastoplasmiques " of P. and M. Bouin, 

 which are said to arise through the breaking down of the spindle 

 fibers and which disappear at the opening of the prophase. Meves 

 and von Korff found similar structures in Litholnns, but these are 

 often present throughout all the stages of mitosis. 



\Yhile these changes have been in progress, the cell has grad- 

 ually been enlarging and by the time of the opening of the 

 active prophase, it is many times its original dimensions. Fig. 

 7, which represents a cell of about average size, has an approxi- 

 mate diameter of seventy-five micra, while occasionally one may 

 attain the enormous size of one-hundred micra. 



Throughout this period, the karyosphere has maintained about 

 the same appearance, excepting its increase in size. During the 

 earlier stages, at the time when the chromatin was accumulating, 

 it appeared to be sharply granular, and to take the stain more 

 densely in some regions than in others ; but as the growth period 

 progresses, the karyosphere, in more darkly stained sections, shows 



