STRUCTURE, ETC., OF PLEISTOPHORA PERIPLANETA. 6238 
lation nearly always, and during the earlier stages usually, 
stain exactly the same tint as the above-mentioned purplish 
nuclei. Occasionally, it is true, these residual nuclei of the 
pansporoblast remain of a bright red tint even when sporu- 
lation is comparatively far advanced. ‘This is, however, 
exceptional. 
The first stage, then, of sporulation consists in the rounding 
off of the trophozoite to form a pansporoblast, and the appear- 
ance of nuclei of two different kinds, the nuclei of the sporo- 
blasts, and the residual nuclei, which disappear with the 
remains of the protoplasm of the pansporoblast. The pan- 
sporoblast (figs. 14, 30—33) is usually a more or less oval 
body, occasionally oblong and rounded at the ends. It is 
almost completely filled with developing spores, all roughly 
in the same stage of development. ‘The interstices between 
the spores are occupied by protoplasm and nuclei, which 
ultimately disappear. The number of spores produced varies 
from three or four (fig. 33) to forty or more. From twenty 
to twenty-five is about the usual number. Lach spore is 
formed from an oval mass of protoplasm—the sporoblast,— 
which rather exceeds in size the spore it produces. In 
stained preparations the sporoblast appears to lie in a 
vacuole. ‘This vacuole is not, however, evident in the living 
cell, and is probably an artifact produced by shrinkage of 
the protoplasm during preparation. It is most marked in 
preparations fixed with osmic vapour and sublimate alcohol, 
although it also occurs in preparations fixed by drying on to 
the slide and immersing in absolute alcohol (figs. 14, 30—32). 
The number of sporoblasts and residual nuclei is roughly the 
same. ‘lhe two kinds of nuclei present, however, considerable 
differences in appearance and staining power. ‘he residual 
nuclei are compact and have a sharply-defined outline from 
the first. With Delafield’s hematoxylin they stain a very 
deep blue; with Giemsa, as mentioned above, usually a deep 
purple. ‘he nucleus of the sporoblast stains differently 
according to its state of development. In the earliest stages 
(figs. 14, 30, 38, 39) it is in the form of a sparse reticulum or 
