Deck. — Injluence 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 montlis 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 

 insufiicient 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 mvicli 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, 

 Paulty dietetics are most likely to obtain just at those months that we have 

 found fco 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 afiected from the onset of the disease as the intes- 

 tinal canal. That which might have been only a simple diarrhoeic 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 oedema 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 



