LIPOID CONTENT OF THE KIDNEY TUBULE 91 
need for oxygen and reducing power of the cells and tissues. In 
1911, Unna showed that the cytopoasm is strongly reducing, 
while the nucleus is oxidative. Kingsbury then says that 
if a close connection exists between reduction processes and cyto- 
plasmic (protoplasmic) activity, and if there is a parallel between 
protoplasmic activity and the demand for and consumption of oxygen 
in respiration, and the mitochondria are structural expressions thereof, 
the question will at once be raised as to the nature of the reducing 
substances, and it will be pointed out that the reducing substances 
that are present in cell respiration may far exceed in power the lipoid 
combinations that are believed to be present in the mitochondria. To 
this two comments may be offered: a) that, whereas, lipoid substances 
seem to be back of the mitochondrial reaction in some cases, it by no 
means follows that the reaction is due in every case to such substances, 
nor does it follow that structures demonstrated as mitochondria are 
in all instances closely connected with cytoplasmic respiration; b) that 
since in regions of the body where the reducing power is markedly 
developed, such as the medulla of the suprarenal gland, the myelinic 
nerve fiber, and the red blood corpuscle, there is an association with 
lipoids, it may well be that such substances are more intimately and 
universally connected with the reduction processes of the body than 
would at first appear. 
From the pathological side, other evidence may be offered in 
favor of the theory that the lipoids in the cell are related to the 
oxidative process. In the first place, there is an increase in 
lipoid content in the kidney in diseases such as tuberculosis and 
pneumonia where there is a decrease in the amount of oxygen 
supplied, and also in anaemic infarcts (Ziegler-Imrie, 715). This 
would suggest that where the oxidation was decreased the lipoids 
were not removed, but stored. Bell (’12) produced this condition 
experimentally in muscle of frog’s leg by ligaturing the leg and 
allowing only a small amount of blood to reach the muscle tissue. 
Others would explain this increase in fat as due to the acid 
production in the cell due to the lessened amount of oxygen 
(Fischer and Hooker, 717). The experimental physiological 
increase (Bell, ’14~’15) might also be explained from the point 
of view that lipoids are reducing agents in cytoplasm, in that 
more lipoids were brought to the cells than were needed by the 
normal processes, and were consequently stored. This would 
be in accord with the idea that they are a reserve fund of fuel. 
