(i.) Due to climatic conditions.
Examples: Heat stroke, diarrhœa in some instances, constipation in many cases, rheumatism, prickly heat, chilblains.
(ii.) Due to errors in diet.
Examples: Diarrhœa, beri-beri, scurvy, sprue(?).
(iii.) Due to poisons.
Examples: Scorpion sting, snake-bite, vegetable poisons.
(iv.) Miscellaneous.
Examples: Bed-sores, epilepsy, apoplexy, concussion of the brain, hay fever, and other conditions into the cause of which a mechanical element frequently enters.
It will be seen that some of these diseases, such as small-pox and diarrhœa, come under more than one heading, but this does not detract from the general utility of the above classification.