PROFESSOR SIMONDS’ LECTURE. 
513 
these periodic meetings, however inviting such a subject might be, 
was a work of supererogation ; for all were ready to admit, from the 
Prince of royal blood to the humble plebeian, that they exercised 
an important influence, both socially and morally, over our rural 
population, and contributed in no small degree to our national 
welfare. In directing their attention to the general arrangement 
and uses of those important parts of the animal organism of which 
he had to speak, it would be necessary to take a rapid glance at 
the process of digestion, for the purpose of placing the office of the 
lungs in a clearer light; as here we trace the formation of the blood 
from the food, and the progress and changes that fluid undergoes 
till it enters the heart; and although he should have chiefly to de¬ 
scribe the respiratory organs, still it must be obvious to all, that he 
must commence by shortly explaining the origin and circulation of 
the blood. 
During life, the continued demand for new material, to supply 
the waste of the tissues which arises from a variety of causes, 
called forth or gave rise to those sensations which we designate 
hunger and thirst. Both the quantity and quality of food which 
was partaken of would, however, depend on the habits and con¬ 
formation of the animal; but in all it underwent a successive series 
of important changes. In the mouth it was masticated or divided 
into smaller masses, during which time it was also insalivated; it 
then passed over the tongue, and descended the gullet into the 
stomach, where it was acted upon by the gastric juice, and he 
might remark, that this action was chemical: in other words, the 
food was here digested. The Lecturer then proceeded to ex¬ 
plain the different changes which the nutritive parts of the food 
underwent after passing from the stomach, until it was formed into 
blood, and referred to drawings of some of the organs through 
which it had to pass during its transformation. He then observed 
that it would likewise be necessary to explain the constituents of 
which the blood was composed, prior to directing their attention to 
the action of the lungs, as the central respiratory organs; for 
unless they possessed some information upon this point, they could 
not rightly understand their functions. Blood might be defined 
to be a fluid circulating through the heart, arteries, and veins, 
carrying the materials of life, renovation, and secretion ; building 
up the system in the young, and supplying the wants of the frame 
in the old animal. But it not only circulated through the system 
for the purpose of building up every part, but also to maintain heat 
in the animal—all animals possessing the power of maintaining a 
heat of their own independent of the atmosphere around them. 
The heart might be designated the central pump from which the 
body derived this fluid; the arteries the transmitting, and the 
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