INFECTIOUS diseases have devastated more homes than all wars combined, and a check to their ravages would be the greatest boon suffering mankind can hope to achieve.
These diseases are supposed to owe their origin to the activity of ferments, enzymes, sporozoa or other ultra-microscopical organisms, consequently they must have some reactions in common with other phenomena depending upon the same agencies.
If true scientific reasoning is based upon inductive methods, namely, 'the endeavor from the much which is observable to arrive at a little which may be verified and is indubitable' then truly our knowledge of ferments is very meager—in fact practically everything we know is deduced from observing the alcoholic yeast ferments, and this for the following reasons: First, they have been employed for many ages. Second, they are larger than the other ferments. Third, they can be studied without jeopardizing fellowmen. Fourth, their chemical effects can be traced in the laboratory, qualitatively and quantitatively, an I last, but not least, their study is not beset with those difficulties which immediately present themselves when effects are produced upon higher differentiated types such as man.
I shall only call attention to such properties which undoubtedly many pathogenic bacteria hold in common with them, namely, we know that these ferments multiply with exceeding rapidity—that they can withstand great ranges of temperature and many chemicals poisonous to man—that they can accommodate themselves to abnormal conditions and remain dormant until suitable conditions again arise and that by their immense numbers much organic material is destroyed. We know, on the other hand, that these ferments have their enemies which can either suppress them entirely or to such an extent as to make them harmless. We know that the introduction of other ferments in the same medium, making use of one of their essential nutrients, may cause a total cessation of their activity—we know that their own excreta or similar products act as poisons upon them. We also know that ferments and enzymes are selective in their foods, probably not from volition, but for reasons of food assimilation.
It is a well-known fact that but an imponderable quantity of a specific ferment is required to start fermentation and this, owing to