THE VETERINARIAN AS A NATURALIST. 
331 
human family, that I desire to emphasize; and also, of the 
changes brought about by pathogenic bacteria in the meat and 
milk supply of our people, which render both inimical as arti¬ 
cles of human food. 
Included in the study of the morphology and physiology of 
these schizomycetes, is, of course, their composition, form, move¬ 
ment, peculiarities of reproduction, the phenomena of respir¬ 
ation and nutrition, the circumstances affecting their growth : 
such as the nature of the soil, temperature, gases, light, etc.; and 
a very important part of the knowledge required regarding 
the pathogenic forms, is a familiarity with their chemical pro¬ 
ducts, or the products of the metabolism induced by them, which 
may be classified as : (i) ptomaines or alkaloids; (2) albu- 
moses or tox-albumins; and (3) enzymes. The first two beino- 
directly poisons ; the third harmless, except in the presence of 
proteids, which they are said to be capable of transforming into 
poisonous albumoses. 
Pathology, so far as studying it in these microscopic death, 
dealers, for the purpose of revivifying and reinstating them in a 
condition of health and vigor, is, of course, out of the question. 
Our main object is their destruction ; and for this purpose vari¬ 
ous methods and agents are adopted, which it is unnecessary to 
mention on this occasion ; but I might allude, just in a word, to 
the fact, that in many instances these very pathogenic organisms 
have been and are being utilized for the production of a thera¬ 
peutic agent peculiar to each—by which the disease, of which 
they are the specific cause, can be prevented and often cured. 
These are the anti-toxins and vaccines; and we are all more or 
less familiar with records concerning vaccination in small-pox, 
and serum-therapy in diphtheria, tetanus, and some other hitherto 
most fatal ailments. 
The word germ, in the ordinary acceptation of the term, seems 
always to carry with it the stigma of disease, but we must not 
forget, that, although the pathogenic forms are both plentiful 
and ubiquitous, to a large extent, there are immense numbers of 
bacteria that are harmless, and many that are really of commer- 
