140 SEVENTH REPORT—1837. : 
we may reasonably hope that a similar result may be obtained 
from the investigation of the processes of nutrition and secretion — 
going forward in living bodies, by regarding them as strictly — 
chemical, even in those very modifications which vitality pro- 4 
duces. When it is considered that during the activity of life 
the process of nutrition is constantly maintaining, even in the 
solid parts of animal bodies, molecular changes by which old ; 
materials are removed and new ones deposited, we must be led 
to presume @ priori, that as the rejected particles are taken away _ 
in a state of perfect solution, they must find their way into those _ 
fluids which proceed from the particular part. In ordinary | 
textures (by which we wish to be understood those which are © 
not called glandular) we fee] no hesitation in admitting that the — 
rejected particles are carried away in the lymph and venous 
blood ; but in glandular structures, and in parts which like them — 
yield a peculiar secretion as well as return lymph and venous 
blood to the system, we have a third course into which some 
of the rejected particles may be expected to find their way. — 
Now though it may be difficult or almost impossible to detect 
either in the venous blood or the lymph, any peculiarities which | 
the addition of the rejected particles may give to the venous — H) 
blood and lymph proceeding from particular parts, the case_ 
may be different when we investigate a particular secretion in — 
which it seems probable that these particles may exist in a 
larger proportion, having a less admixture of the whole or some 
of the constituents of the general circulating fluid. The mani- 
fest properties of some secretions seem to lead to a similar con-_ 
clusion & posteriori. The varieties which we find in pus ae 
duced in different parts of the body are among the most pal-— 
pable examples of this kind. Pus from the brain has a peculiar 
consistence and colour resembling greenish cream, even where — 
there has been no breaking down of the substance of the brain, — 
by which that material might be grossly blended with it. When 
pus is formed in the immediate neighbourhood of the alimentary 
canal, and especially of the lower part of it, it possesses so strongly — 
the iecl odour, that it had been confidently believed that faeces 
had been mixed with it, until the absolute impossibility of such 
an occurrence had been demonstrated. Pus formed in the im- 
mediate neighbourhood of the toes possesses the peculiar odour 
of those parts, and a similar remark sometimes applies to matter 
formed in the axille. 
The peculiar odour exhaled by different species of animals, 
and even by different individuals of the same species, dependent 
on differences of age and sex, appears to be another illustration 
of the principle which has been here suggested: for although 
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