8 
Transactions Texas Academy of Science. — 1907. 
quantity of blood into the system, although the -balance of power is 
finally restored by another process, namely, compensatory hypertrophy. 
Of course, the call on this reserve power produces a wasteful metab- 
olism in the tissue cells, and, if the call is too prolonged, we reach 
a point spoken of as the breaking strain, where the organ fails com- 
pletely to carry on extra work and is often unable to functionate at all. 
It is rather difficult to understand what this represents chemically, but 
it has been compared to the phenomenon of supersaturation. If a 
supersaturated, hot solution of Glauber’s salts be allowed to cool and 
be kept perfectly quiet without vibration, it will remain fluid, but if 
shaken or touched with a glass rod, or a crystal be dropped into it, the 
whole immediately crystallizes. It has also been compared to coagu- 
lation, for it is found that a totally exhausted muscle which has drawn 
^extensively on its physiological reserve falls immediately into a condi- 
tion of rigor mortis after the animal dies or is killed. 
The central nervous system possesses physiological reserve to the 
highest degree, and, being highly organized tissue, it responds like a 
highly-bred animal to calls on this reserve until it is exhausted; and 
then, as Abrahams has aptly expressed it, like a man who has been 
living on his capital, there comes a day when the funds are exhausted 
and the tissues are bankrupt. 
The chemical changes occurring in the neurons as a result of exces- 
sive mental activity, are little understood. We know, however, that 
their complexity increases with education, and, pari passu, there arises 
a greater vulnerability, which is always increased by overwork, particu- 
larly if the patient has suffered from syphilis or has been addicted to 
the excessive use of alcohol. An astonishingly large proportion of 
insane people suffering from general paralysis have been men and 
women of unusual mental power and activity. 
Let us now turn our attention to some of the chemical processes by 
which organs are able to produce secretions necessary for the contin- 
uation of life. 
Commencing with the alimentary canal, we find that the very foods 
introduced are teeming with micro-organisms, which, far from being 
hurtful, are as necessary probably as those found at the rootlets of 
plants. The digestive juices themselves are destructive to the struc- 
tures that produce them, if there be any injury to the epithelium. 
Thus the gastric juice has the power of digesting injured and necrotic 
mucous membrane, and exerts a very deleterious effect on the duodenal 
mucous membrane, if the acid chyme fails to be neutralized by the 
alkaline bile and pancreatic juice. Further, the secretions of the pan- 
creas are a source of danger to the gland itself, if they are retained as 
a result of obstruction of the duct, as is shown by the appearance of 
