PHYSIOLOGY OF DIGESTION IN BLATTIDAE 361 
Perenyi’s fluid. In the American cockroach there is a definite 
region of the anterior crop where there are very few muscles, 
this region is especially favorable for study. In these prepara- 
tions the epithelial cells appear mostly as hexagons. 
Petrunkevitch has described certain unusual conditions in 
some of these cells, and has figured them as seen when flat and in 
cross sections. In some cases the cell walls of a group of cells 
degenerate and the cells fuse. The cytoplasm appears vacuo- 
lated and abnormal and the nuclei begin to degenerate. Finally 
the whole mass of protoplasm seems to be discharged and the 
gap filled by the growth and cell divisions of adjacent. cells. 
He also describes cells which contain two or more nuclei, but do 
not appear abnormal otherwise; these represent small syncytia 
resulting from nuclear divisions with suppressed cytoplasmic 
divisions. 
Among my preparations some slides show stages which may be 
likened to these. The cells show great inequality of size, the 
very small ones appear to be latent, but ready to replace by 
growth any gaps in the epithelium. Binucleate and trinucleate 
cells often appear, but I cannot explain their significance, per- 
haps they represent small syncytia. Some of them are shown 
in figure 18. Another unusual condition is shown in figures 17 
and 18. In such cases the cytoplasm appears abnormal and 
numerous nuclei are present, some of them appearing degenerate 
or as mere vesicles. No traces of cell walls are present in these 
regions, and the cytoplasm seems dead. I have been unable to 
.find a definite explanation of such pictures; perhaps they repre- 
sent a sort of lesion which results from injury to the cells through 
mechanical damage by sharp pieces of food or through the ac- 
tion of poisonous matter in the food. The process cannot, I 
think, be compared with the normal casting of cells of the 
stomach epithelium after they have become worn out by continual 
functioning. 
Petrunkevitch has also figured ring cells; that is, cells which 
contain a very large vacuole surrounded by a thin layer of cyto- 
plasm containing the nucleus. He believed that these cells 
represented a stage in the fusion and casting of cells, especially 
