88 CHRISTIANNA SMITH 
The rods of the ascending limb of Henle’s loop again show their 
fatty nature, both in dichromate fixation and 1 per cent osmic 
acid. 
Rat 
The kidneys of rats were also examined and the results in 
general were like those obtained after the study of the renal 
cells of the rabbit. The kidneys of nineteen rats were cut and 
fixed. All of these rats were infected with lice, but the internal 
organs appeared normal except for one case of a cystic liver and 
one kidney that proved to be pathological when examined 
microscopically. Kidneys of rats which had been fed on fat 
diets were studied, and both these and controls were subjects 
to autolysis with fixation accompanied by heat. The results 
in brief were as follows: The rats possessed interstitial lipoid 
granules, which were especially abundant in the papilla. The 
presence of these granules made it difficult in the case of osmic- 
acid fixations to distinguish always between intracellular and 
interstitial lipoid granules. In the fresh tissue and that preserved 
in formalin, the interstitial were the only lipoids that seemed 
to be present. Tissue fixed in 10 per cent dichromate with heat 
and stained with sudan III possessed granules which Bell would 
clearly call sudanophile precipitate, for they were not observed 
in the fresh condition. However, if lipoids which stain with 
osmic acid can be liberated after autolysis and fixation in an 
incubator, then it does not seem unreasonable to believe that 
some lipoids in combination in the cell might be sensitive to heat 
and liberated by it, chromated, and stainable with sudan III. 
Bell admits that more fat is demonstrable when higher tempera- 
tures are used, but does not yet interpret the sudanophile precip- 
itate as diffuse fat. The granules were found in all the cells and 
the cytoplasm was unstained. The results with Benda’s were 
the same as those observed in the rabbit. 
Experiments to show the effect of fat diets were also carried 
out. This feeding was mostly on fat meat and bread soaked in 
fat, one rat was fed olive oil twice on the day it was killed. There 
was no infiltration of annular droplets as described by Bell, 
