These classes of remedies are often confounded together. It is well, however, to distinguish their meanings: Antizymotics are remedies which arrest fermentation.

It has already been mentioned (p. 73et seq.) that fermentative processes may depend upon either enzymes or organised ferments, and that organised ferments may be subdivided into several classes, such as those consisting of yeast, innocuous bacteria, and pathogenic bacteria.

The class of antizymotics includes all substances which arrest fermentative processes due to these bodies. It contains two subclasses : antiseptics and disinfectants.

Antiseptics are remedies which arrest putrefaction. They do this by preventing the development, or completely destroying the bacilli on which septic decomposition depends.

Disinfectants are remedies which destroy the specific poisons of communicable diseases. Many of those poisons, perhaps all of them, belong to the class of microbes, and so disinfectants may be regarded as a sub-class of antizymotics.

Deodorizers or deodorants are remedies which destroy disagreeable smells. Such smells often accompany the decomposition of various organic substances, which septic organisms cause. These foul-smelling products may be injurious to health in themselves by acting as poisons; but they are not to be confounded with the bacteria which produce them. Moreover, the disagreeable nature of the smell is not always to be relied upon as an index of its poisonous nature. M. Gustav le Bon made some experiments with hashed meat and water, over which he put some small animals. As the meat decomposed, the liquid teemed with organisms, was very fatal when injected into an animal, and emitted a very foul smell, which, however, did not seem to be very injurious. Afterwards the organisms present in the liquid died, and the foul smell became much less disagreeable; but the emanations from the liquid appeared to become much more poisonous, although the liquid itself, when injected into an animal, had no longer the same virulent power as at first.