DecK.— Influence of Temperature on Infant Mortality. XLI 
disease manifests its power upon infants in whom this process, commonly 
speaking, has not yet commenced. By the time that the first molar teeth 
usually make their appearance, the susceptibility to the disease is nearly past. 
Whatever the process of dentition may have to do in favouring this suscepti- 
bility, it must be the development of the teeth in the bony structure of the 
jaws rather than their eruption through the gums that acts unfavourably. 
But there are other considerations that lead to the conclusion that there 
are agencies at work during these early months of life in producing this 
susceptibility other than the process of dentition. Cholera infantum seldom 
attacks in a severe manner children that are properly nourished, and at no 
period of life do causes of mal-assimilation of food, and consequently of 
mal-nutrition, exist so frequently as during these first eight or twelve months. 
Suppose a child for whom the maternal supply of food is poor in quality or 
insufficient in quantity, and that there is a want of suitability in the nourish- 
ment that has been given to make up the deficiency, mal-nutrition must be 
the result. How frequently do such cases occur! How much more likely 
are they to present themselves during these early months of life than afterwards 
when the digestive organs are more fitted to act upon a variety of food, 
Faulty dietetics are most likely to obtain just at those months that we have 
found to be most fatal to infant life. 
Their intimate connection is still further apparent when we consider the 
organ that this mal-nutrition will act upon with the greatest intensity. Dr. 
West says, “There is no organ in the body, with the exception of the 
pregnant womb, which undergoes such rapid development as the brain in 
early childhood. It doubles its weight during the first two years of life.” 
The brain, then, and the medulla oblongata, the head-centres of nervous life, will 
be the organs upon which this mal-nutrition will be most injurious. And we 
can readily understand how injurious the depressing influence of high tem- 
perature must be on a system in which these important organs are in a weak, 
badly nourished, state. And we find in all severe cases of cholera infantum 
that the brain is as much affected from the onset of the disease as the intes- - 
tinal canal. That which might have been only a simple diarrheic attack 
from some passing irritation, is changed into a severe, perhaps fatal, intestinal 
disorder through this weakened state of the brain and nervous system. The 
intimate connection that exists between the two I need not now enlarge 
upon ; the effect upon the intestinal canal of any sudden shock or emotion, 
which must act through the brain, is well known to everybody. ` I will only 
‘add that the recent experiments of Ranvier throw some light on the nature 
of this connection. He has shown that edema of the leg may be produced by 
section of the vasomotor nerves which supply its vessels, and does not follow 
ligature of the femoral vein. He has demonstrated that venous congestion 
