8o PATHOLOGY: UNDERHILL, HON EI J AND BOGERT Proc. N. A. S. 
metabolism must stand in sharp contrast. The Hterature contains little 
data relative to mineral metabolism in either of these diseases. 
In the present investigation the general plan followed was to place the 
subjects of experimentation upon a known diet low in calcium and mag- 
nesium for a definite period. Calcium or magnesium was then added for 
a second period. Calcium intake was increased by the administration 
of milk. Magnesium was given in the form of the citrate. By the pro- 
cedure outlined it is apparent that the organism was given a distinct task 
to perform. The manner in which this task was accomplished by the 
diseased organism was judged by comparison with normal subjects main- 
tained under similar experimental conditions. 
The experiments were made upon six subjects divided as follows : 
(a) 2 normal subjects, {h) 2 leprous subjects, (c) 2 exostosis subjects. 
In the study of leprosy one subject represented a well-advanced case; 
in the other the disease was in an incipient stage. 
With exostosis one subject had advanced to the stage where the abnormal 
processes had become stabilized; the other case represented the active, 
less advanced stage of the disease. 
Results. — ^When compared to normal individuals under the same experi- 
mental conditions leprous patients retain calcium in relatively large quan- 
tities whether the individual is maintained upon a calcium-poor or a 
calcium-rich diet; and the greater the intake of calcium the greater is the 
relative retention. In the more advanced stage of the disease the degree 
of retention is greater than in the early phase. 
This retention cannot be explained by differences in calcium intake or 
by variation in the power of absorption. It is apparently an evidence of 
a metabolic demand for calcium induced by the disease. Clinically, it 
may be inferred that there is a need for calcium; experimentally, the or- 
ganism gives evidence of this need by retention of calcium administered. 
The study of magnesium exchange in normal and leprous subjects demon- 
strates that in the advanced stage of leprosy there is a tendency for a re- 
tention of magnesium. The degree of retention is much less marked than 
in the case of calcium. 
With the exception of the retention of calcium and magnesium the leprous 
organism responds to changes in intake of calcium and magnesium in 
the same manner as that exhibited by the normal subject. • 
It is, perhaps, self-evident that the loss of bone salts in leprosy is but a 
manifestation of the disease processes. Nevertheless it is quite conceiv- 
able in dietary conditions where calcium is not particularly abundant that 
the lack of this element may play a material r61e in the rapidity of the 
progress of the disease. Conversely, the suggestion is pertinent that the 
progress of the disease may be greatly retarded or perhaps even alleviated 
if an abundance of calcium is present in the diet. 
