Many maladies of plants are traceable to the chemical composition of soilse.g.
As regards water, its deficiency or excess is a relative matter, and although many of the minor maladies of pot-plants in windows and greenhouses controlled by amateurs depend on its misuse, water alone is probably never a primary cause of disease.
By the discovery of the bacillus of tubercle, the physician has been enabled to piece together a long and varied list of maladies under several names, such as scrofula and lupus, many of them long suspected to be tuberculous, but now known to belong to the series.
The conditions of diet and digestion in children are now far better understood, and many of their maladies, formerly regarded as organic or incomprehensible, are cured or prevented by dietetic rules.
Vesque, Les Maladies des plantes cultivees, pp. 98-105 (Paris, 1878).