C) 34 CONSIDERATIONS AND EXPERIMENTS 
one of laceration and dilatation of the oesophagus,‘in the part, 
in a state of health, the least susceptible of dilatation;—of 
hypertrophy of the fleshy coat at this part;—of the formation 
of a sac, lodged between the lobes of the two lungs;—of aug¬ 
mentation of the calibre of the terminating portion of the 
cesophagean tube, which will account for the vomiting. But, 
did the matters ejected through the mouth and nose come 
from the sac or the stomach, or from both sac and stomach? 
I believe myself in the first of these hypotheses, and for these 
reasons:—1. That autopsy showed the stomach free from 
alteration. 2. That the abdominal muscles appeared to me 
unconcerned in the acts of vomition. 3. That the sac being 
large enough to hold nearly three pints of fluid, and that 
after the horse had drunk, the fluid, returned by the mouth, 
being about three pints. Thus, physiologically, one might 
conceive that, through the influence of a deep inspiration, the 
lungs, being at the time greatly dilated, the sac might be 
compressed and emptied, and so they become the active 
agents of vomition.— Rec . de Med. Vet., Mai , 1852. 
CONSIDERATIONS AND EXPERIMENTS RELATING TO 
CONTAGIOUS DISEASES. 
(Lectures delivered to the College of France by M. Magendie.) 
In these lectures, M. Magendie 5 s object has been to examine 
into the channels through which deleterious substances find ad¬ 
mission into the animal economy . 
Respiration is the principal one. Through it we are continu¬ 
ally exposed to the action of gases, vapours, emanations, 
virulent and caustic poisons, germs and seeds, the ulterior 
development of which may entail mortal results. The ma¬ 
jority of substances thus introduced are of a nature to alter 
the composition of the blood, and disturb its vital operations. 
The vapours have divers chemical compositions. Some 
there are which have the power of quickly extinguishing the 
nervous energy. And although not many of them possess 
this fatal property, it no less becomes our duty to inquire 
into their mode of action. At the head of these we must 
place prussic acid, a substance so volatile that it condenses 
while evaporating. Magendie illustrated this by experiment. 
He mixed, in a conical vessel, a spoonful of medicinal prussic 
acid in combination with three-fourths of alcohol and one- 
