REPORT OF MEDICAL SECTION. 141 
such peculiar odour may in some instances be referred to a spe- 
cial local secretion, as in the instances of the civet cat and musk 
deer, it cannot have escaped the observation of those who have 
been in the habit of dissecting the bodies of recently killed ani- 
mals of different species, that these exhale not from one part 
only, but from every part internal as well as external, modified 
indeed by circumstances, a peculiar smell which is characteristic, 
and belongs both to the solids and fluids. 
- Another illustration of the influence of the character of parts 
upon the secretion which they produce may be seen about the 
mouth, where a slight excoriation or sore is apt to produce a 
considerable quantity of thin fluid secretion, which one can 
searcely fail to regard in conjunction with that secretion which 
is poured into the mouth from the internal surface of those 
parts. The copious secretion from a blistered surface, when the 
subcutaneous cellular membrane is cedematous, is perhaps a 
phenomenon of the same character. 
The chemical composition of secerning organs may influence 
that of their products independently of the particles which they 
may absolutely impart from their own structure. It may do 
so by a process similar to that which Thenard has pointed out 
as taking place when deutoxide of hydrogen comes in contact 
with fibrin ; a process which that great chemist several years 
Since pointed out as likely to throw light on the function of 
secretion. This idea has since been developed by Berzelius, 
who calls their action of contact the catalytic action, and argues 
that probably the contact of the blood with certain surfaces of 
the organs may produce some alteration in the arrangement of 
elements, and that the secretions may be thus catalytically 
formed from the blood. 
_ It is probably to the operation of this principle that we may 
ascribe some phenomena, which, in addition to the circumstances 
which have already been mentioned, render it desirable to ascer- 
tain with accuracy the composition of solid parts in conjunction 
with that of their secretions. In some healthy, and in not a few 
morbid actions, we see that a new product, whether fluid or solid, 
is verymuch influenced by the character of the surrounding parts. 
Thus in the condensed cellular membrane in the neighbour- 
hood of bone it sometimes happens that masses of bony matter 
are deposited, but are perfectly detached. The numerous in- 
stances which we see of ossification at the origins or insertions 
of muscles are probably referable to the same principle; although 
| it must be admitted that these examples are not unexceptionable, 
| Since in them we have a continuity of structure. As a further 
| illustration it may be noticed, that after the fracture of a bone, 
| 
| 
