NERVE CELLS OF THE CRAYFISH o7 
sheath cells. They indicate a delicacy and an intricacy of 
Structure of the trophospongium more marked even than pre- 
viously reported (Ross, 715). The finely filamentous structures 
described by Poluszynski (’11) in Homarus may well have been 
trophospongium stained by the reticular methods, since hedid 
not appreciate the extreme delicacy of this supporting framework. 
Mitochondria 
‘“Mitochondria may be provisionally defined as substances 
which occur in the form of granules, rods and filaments in almost 
all living cells, which react positively to Janus green and which, 
by their solubilities and staining reactions resemble phospholipins 
and, to a lesser extent, albumins”’ (Cowdry, 716, p. 425). 
Altmann added another element to the known complexity of 
the nerve cell a quarter of a century ago when he observed that 
in adult nerve cells there are minute bodies now known as mito- 
chondria. Since that date the literature upon mitochondria has 
become voluminous, although most of the work has been of 
recent years. Mitochondria are now known to be present in 
the cells of nearly all tissues of both animals and plants. ‘‘ They 
(mitochondria) occur in almost all cells . . . they are as 
characteristic of cytoplasm as chromatin is of the nucleus”’ 
(Cowdry, ’16). Mitochondria are readily demonstrable in the 
crayfish ganglia, in the cell bodies and along the course of the 
fibers. Such variations in size and shape as are usual in cells 
from other sources are to be observed here. Some are granular, 
others short rod-shaped, or of longer rods, straight or slightly 
bent; granules or rods isolated or grouped or arranged in rows 
giving a broken line appearance (figs. 9 to 12). 
As it was not the purpose of the study to investigate the 
technic of mitochondria staining, only a few methods were used. 
A few trials of Regaud’s method (’10) were made without satis- 
factory results, as no mitochondria were made evident. Janus 
green gave its typical reaction. Bensley’s acetic-osmic-bichro- 
mate acid-fuchsin method yielded the best results. Although 
this stain is not permanent, yet it was retained quite distinctly 
for two and one-half years or longer. 
