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PROCEEDINGS OF SOCIETIES. 
Besides, they had special ai)pcarances in some diseases ; thus, in in- 
flammation of the lungs they had minute oil globules, numerous blood 
corpuscles, and granular spherical cells. The yellow spit of bronchitis 
abounds in pus cells and epithelium in all stages of growth. In the 
spit of consumption they also found pus corpuscles or globules, and 
peculiar bodies called tubercle corpuscles, of an oval form, but with- 
out nucleus ; also, at an early stage of the disease, fragments of lung 
tissue, which were invariable evidence of the disease. Having alluded 
to the advantages to he gained from a microscopical examination of 
vomit, Dr. Thomson proceeded to speak of the most important part of 
his subject — the examination of diseased growths and tumours. This 
part of the paper we give in full, as follows : — “ It becomes often of 
the utmost importance to determine the nature of one of these growths 
after removal by the surgeon’s knife ; and it often rests with the 
microscopist alone to settle the question as to whether a return 
of the disease is likely. Even before removal it is sometimes pos- 
sible, by detaching a minute portion of the tumour, to subject it to 
the microscope, and to decide as to the probability of an operation 
effecting a permanent cure. The increase to our knowledge on this 
subject alone, since the microscope was brought to bear on it, has 
been simply invaluable ; and I have not a doubt in my mind but that 
we are on the eve of discoveries still more important, which may be 
the means of averting, in a great measure, some of the most dreadful 
diseases that scourge mankind. There are two grand classes of 
tumours. In the one you have the tumour produced by irregular 
growth of some tissue of the body, and consisting simply of the 
elements of that tissue. Such are fatty, and bony growth, and many 
others, of which you have a familiar example in warts, wdiich are 
simply an irregular growth of the skin, and are composed of the same 
elements. These are simply deformities, and fraught with no danger 
to life, unless under extraordinary circumstances. The other class, 
however, is very different. Here we have structures not comparable 
to any natural tissue of the body. Such are all kinds of cancerous 
growths, to which I shall come presently. Now, it is considered a 
fact beyond dispute that every tissue in the body results from changes 
that have taken place on germinal or growing matter. The tissue is, 
in fact, formed matter. Also, that this growing matter was derived 
from other growing matter which existed before it, and which may 
even have had different properties from it. Now, in every healthy 
tissue you will find small collections of growing matter, from which 
new tissue is formed from time to time, to replace what is wasting 
away during the performance of its function, or when a portion has 
been destroyed by disease. And the rate of formation of this new 
tissue is in proportion to the destruction of the old tissue. Now, 
suppose that one of theso germinal masses should become displaced 
by an accident, such as a blow, or from some other cause, should 
become irregularly supplied with nourishing material from the blood, 
and, in consequence, sprout into active growth when not required, the 
result would be a shapeless lump of tissue, in fact, a tumour. Now, 
this tumour having no office to perform, and hence no waste to 
undergo, continues to grow just as a healthy tissue would do, there 
