TROPHOSPONGIUM OF THE NERVE CELL 520 
capillaries become so small, one-half micron or less in diameter, 
that the supporting chitinous spirals or taenidia are absent. 
There is no morphologic resemblance to the trophospongium 
which is present in the grasshopper and cockroach cells, although 
not so strongly developed in these insects as in the crayfish. 
The nerve cells of the abdominal ganglia of the crayfish, 
Cambarus, afford excellent material for the study of the 
trophospongium, as some of the motor cells are large and the 
trophospongium well developed. The ganglia may be fixed 
and stained by Bensley’s acetic-osmic-bichromate acid fuchsin 
method, or fixed in Zenker’s fluid and stained with Mallory’s con- 
nective tissue stain. Other methods will doubtless give good 
results also. It is not necessary to use perfectly fresh tissue, as 
good results were obtained with ganglia from animals dead several 
hours. Both large and small cells contain the trophospongium, 
although it is more strongly developed and more prominent in 
the large cells and was not observed in many of the smaller. Nor 
does it show in equal degree in all the large cells, due in part 
possibly to a difference in response of the cells to the technique. 
The examination of serial sections, 4 micra in thickness, shows 
that the structure is not a reticulation of fibers but is an anasto- 
mosis of partition walls or of capsules extending into the cyto- 
plasmic mass and dividing it into irregular lobes differing both 
in shape and in size. The cytoplasmic mass is continuous, 
however, as the lobes are only partially separated one from 
another by the incomplete partition walls. Some of the lobes 
are broad and flattened while others are somewhat conical or 
cylindric in outline. The trophospongium in some instances, 
as seen in sections, appears as a relatively low ridge rather broad 
at the base and giving off short, delicate branches near the free 
margin. In other sections, approaching the tangential sections, 
the ridges extend across the section, not infrequently almost 
parallel and connected by means of cross partitions. Near the 
center of the cell some sections show the structure extending into 
the vicinity of the nucleus, apparently as delicate fibrillae. The 
study of serial sections gives a conception of the trophospongium 
