80 CHRISTIANNA SMITH 
these are called mitochondrial rods, and although Benda con- 
siders them mitochondria properly speaking, Policard does not 
agree for the following reasons: 1) Mitochondria are flexous 
filaments, and these rods are like sticks arranged in bundles, on 
cross-section appearing like cardiac muscle (’05); 2) these 
‘batonnets’ are more easily preserved than mitochondria, although 
mitochondrial technique brings them out more clearly (710); 3) 
mitochondrial filaments in the proximal convoluted segment 
vary in form, becoming at times granular normally and during 
autolysis, while the rods of the third segment (which corresponds 
to the ascending limb of the medullary loop) never becomes 
granular normally nor during autolysis (10). As to their nature, 
Policard describes them as, “protoplasmic rods, the surface of 
which seems to be covered with a lipoid substance”’ (710). 
That these rods are lipoids or fatty in nature is shown very 
clearly in these sections, and it is because sudan III is solublein 
them that the region of the medulla next to the cortex is stained 
more deeply red. In thin sections where the rods were not so 
closely packed that their individuality was hard to determine, 
_ two types could be distinguished. One form corresponded to 
the homogeneous rods of Policard, and they appeared like annular 
droplets drawn out to form rods which varied in length and width, 
some being slightly irregular. It may be possible that the 
method of fixation with the heat may have affected some of the 
rods and that they were atypical. The other form was composed 
of small granules arranged in rows (fig. 9). This form of the 
rods is quite contradictory to Policard’s description of them. 
Small annular droplets and solid granules were present which 
might be interpreted as sections or tips of rods or distinct in 
themselves. 
The distal convoluted tubule had epithelium of the same 
heavily rodded character as that of the ascending limb of the 
medullary loop, and the cells of the collecting tubules contained 
a few solid fat granules. One portion of the renal tubule has 
not been discussed and that is Bowman’s capsule. The flat 
epithelium of the capsule also possesses lipoid granules, as do 
the other segments of the tubule. 
