on Animal Heat, 6oi 
that they will be found correct when repeated, what are their 
consequences in a theoretical point of view? 
They are evidently in direct opposition to Dr. Crawford's 
hypothesis ; the essence of which is, that the capacity of ar- 
terial blood for heat is greater than that of venous, that there 
is no difference of temperature between the two ventricles of 
the heart, and in fact that the heat of all parts is nearly the 
ft 
same. 
They are more agreeable to, and indeed they even support 
the hypothesis of Dr. Black, that animal heat is produced in 
the lungs, and distributed over the whole system by means of 
the arterial blood. 
Neither are they inconsistent with that hypothesis which 
considers the production of animal heat as dependent on the 
energy of the nervous system, and arising from all the vital 
actions constantly occurring. 
Besides the results of the preceding experiments, many ar- 
guments may be advanced in opposition to Dr. Crawford's 
hypothesis. 
As we never perceive a difference of capacity in bodies 
without a difference of form or composition ; and as very 
slight differences of the former result only from great changes 
of the latter, it might be expected a prio?i, as no difference, 
excepting that of colour, has been detected between venous 
and arterial blood, that their specific caloric would be very 
similar. From analogy also, it might have been expected, that 
the capacity of arterial blood for heat would be much less than 
that of water, as \tater appears to exceed almost every other 
fluid, and as the capacity appears to diminish as the inflamma- 
bility of compounds increases. But the strongest arguments 
