71S 
ON TUBERCLES IN DIFFERENT ORGANS. 
Tubercles are parasitical organs, — according to this gentleman, — 
generated in the economy, with an organization that enables them 
to increase by introsusception. It matters not in what tissue they 
are generated. With a slight difference in the form, they are the 
same wherever they are found; whereas they would be dissimilar 
in each organ, and in each tissue, if they were the products of 
inflammation. 
Pneumonia is one of the most common maladies a surgeon is 
called upon to treat. If it were really the proximate cause of 
tuberculization, it would be easy to perceive the relation between 
inflammation as a cause, and the generation of tubercles as an 
effect. This, however, is not the case. No one has proved any 
connexion between the two. Bayle opened many patients that 
had died of chronic latent pneumonia : he found the lungs hepa- 
tized, carnified, but never the seat of tubercles. Epidemics of 
pneumonia are by no means rare, but there has been no epidemic 
in which any great proportion of the inhabitants in which it has 
raged has become phthisical. It is, perhaps, doubtful whether 
pneumonia tends to increase tuberculization in the pulmonary 
tissue. 
It is worthy of remark, that the theory which attributes the 
formation of tubercles in the lungs to inflammation has been 
often adopted and defended by pathologists who never would 
have thought of attributing the generation of tubercles of the 
liver to hepatitis — of tubercles of the spleen to splenitis — or of 
tubercles of the brain to encephalitis, although the same law neces- 
sarily presides at their formation. 
Some pathologists look upon tubercles as an alteration or pro- 
duct of secretion. Tubercles are supposed to be inorganic bodies, 
deposited in the tissues, and formed by the gradual deposition or 
incrustation of secreted matter : the tubercle, therefore, is deve- 
loped by the continual addition of particles of tubercular matter 
secreted in the same manner. Judging a priori, and without 
consulting nature, this appears a very simple mode of explaining 
the formation of tubercles ; but if we analyse it, the error is 
immediately evident. In all bodies that increase by juxta-position 
we find the traces of the successive aggregation of the molecules. 
If we examine almost any kind of tumour, we find the successive 
layers of which it is formed ; but the structure of the tubercle is 
perfectly homogeneous, and there are no successive layers. It 
should be also recollected that tubercles exist every where, and in 
every tissue; whence it would follow that a substance always 
identical is secreted by the most dissimilar tissues, whenever the 
general predisposition which appears to preside over the mani- 
festation of tubercular structure exists. 
These theories are all erroneous, and we are driven to the belief 
that epigenesis is the only principle that will satisfactorily account 
for tuberculization. By epigenesis we mean the formation of organ- 
