LIPOID CONTENT OF THE KIDNEY TUBULE 89 
although with sudan III the granules appeared more numerous 
and somewhat more intensely stained, and a few faintly stained 
lipoid droplets were present in tissues fixed in an osmic-acid 
solution. These results did not check Bell’s work. This may 
be because the feeding was not forced. 
GENERAL DISCUSSION 
As it was stated in the introduction, the conclusions reached 
in this study of the lipoid content of the kidneys were that 
lipoids could be demonstrated in kidney cells by special technique, 
that the distribution and formations of lipoids were more charac- 
teristic in some species than in others, and that some lipoids 
appeared to be intracellular in origin. The very definite distri- 
bution of the lipoids in the kidney of the cat has been shown, a 
distribution not so marked in the dog, and still less so in the 
rabbit and rat. However, in one segment there were lipoid 
formations peculiar to them all. These were the rods in the 
ascending limb of the medullary loop. As it was pointed out in 
reference to the cat and dog, these rods are lipoid in nature and 
are resolved into filaments composed of lipoid droplets under 
certain conditions. As these rods were considered by Benda 
mitochondria, properly speaking, and were called mitochondrial 
rods by Policard, although he denied their identity with them, 
the suggestion that there is a close relation between these rods 
and the formation of lipoid droplets in the cell ought not to be 
overlooked. In the granular forms which were seen after a 
fixation in 10 per cent dichromate and sudan III, a shadow of a 
rod could be seen between the granules. After a fixation in 
potassium dichromate and osmic acid, the droplets stood out 
clearly and separately in a definite linear arrangement. The 
presence of lipoid droplets in a linear arrangement in cells of 
other parts of the renal tubule is also very suggestive, although 
the evidence of their origin is not clear. Scott (716), in his work 
on the effect of phosphorus poisoning on mitochondria in pan- 
creatic cells, says that after the mitochondria lose their filamen- 
tous form that they agglutinate and fuse to form droplets 
possessing the characteristic properties of lipoids. Mitochondria 
