I may here allude to the circumstance, that in the island of Cuba, the destructive mildew is commonly called, la pesta.
It were needless to multiply instances of other endemic and epidemic diseases of vegetables; they are well known by practical observers to be very numerous, and I believe, in most instances, depending upon fungoid growths. The destruction of vegetables by insects, is of a very different nature to that produced by the fungi; it would be as unreasonable to consider the consumption of corn and herbage by locusts, as a disease of vegetation, as the massacre and devouring of human beings by cannibals, a disease of the human body.
It is true that insects are exceedingly destructive to plants, but as far as I am able to obtain information, they appear to be so chiefly by their voracious propensities; they consume the structure of the plant in its entity, and do not primarily interfere with its vitality. The instance of the vibriones, before-mentioned, seems at first to be an exception
to the rule, but this is rather apparent, than real; and it may be made to apply more as a confirmation, than an obstacle to the vegetable theory: for if we may fairly compare the diseases of animals with those of plants, the existence of entozoa in the latter, would be considered an essential point to be substantiated.
Having now considered the question as to the infeasibility of supposing that chemical fermentation is the basis upon which a theory of diseases can be sustained, and having shewn that life is inseparable from infection, and miasmatic generation;—having explained the phenomena of the dispersion of diseases by comparison with the dispersion of plants, and finally, having demonstrated that the physiology and pathology of plants bear so close a relation to each other, and that their epidemic affections depend upon minute organic germs, I submit to the judgment of my readers, whether there is not much reasonableness in the application of the facts to the inference—that living germs are the cause of epidemic disease in man and animals.
CHAPTER IV.
RESULTS IN PROOF OF THE TENABLENESS OF THE PROPOSITION.
————