Laboratory and Field Manual of Botany (1907)

Whatever the mental cause of this melancholy, there is no doubt that it had also a physical cause. This was his most violent attack, but by no means his only one. It recurred, with greater or less severity, all through his life. He had been born and had grown up in a climate noted for its malaria. Excepting for the facts that he spent much time in the open air, had abundant exercise, and ate plain food, the laws of sanitation were not thought of. It would be strange if his system were not full of malaria, or, what is only slightly less abominable, of the medicines used to counteract it.