n6 POPULAR SCIENCE MONTHLY. 



very careful in avoiding infected persons, and would even seek their 

 company so as to get infected from them. The practice of intentionally 

 rubbing one's skin with a pustule, or with bits of it, from an attacked 

 person, must have been a subsequent stage. 



Such or a similarly gradual development of ideas may explain why 

 it is impossible to fix a date or place for this discovery, which indeed 

 goes back to the darkness of antiquity. Kesearch points to its practice 

 among the Chinese and Hindus in very ancient times. The Chinamen 

 induced a mild attack by inserting a crust from a smallpox pustule into 

 the nostrils. The Hindus, on the contrary, used the fluid pus, which 

 they inoculated under the skin of the arm. In either case, in the course 

 of a week, the inoculated was attacked by some slight preliminary 

 symptoms followed by an eruption, sometimes profuse, sometimes 

 scanty, and then the disease would run its ordinary course. The only 

 difference between an attack caused by inoculation and that caused 

 by natural infection was, as a rule, the milder nature of the former, 

 especially when the matter for inoculation was taken from a notoriously 

 mild case. The result, however, was by no means certain. A mild 

 form of an infectious disease may be due either to the virus be- 

 ing of a weak nature; and then such a virus would be the 

 desired one for inoculating persons seeking artificial protection; or 

 else the mildness of the case may be due to the patient himself being 

 of a resistant organization, in which case, though exhibiting mild 

 symptoms himself, he may be harboring an intense form of contagion, 

 apt to cause a severe outbreak when transferred to other less resistant 

 persons. Many plans were consequently adopted to secure with more 

 certainty a mild artificial infection. Some of these were directed to 

 the treatment of the patient preparatory to inoculation, others to the 

 preparation of the infectious matter in order to attenuate its virulence. 

 The Brahmans, who were the operators in India, in addition to selecting 

 material from patients with a mild form of the disease, were accus- 

 tomed not to employ the pus at once, but to keep it wrapped up in 

 cotton wool for a period of about twelve months, and thus to weaken 

 its power. They inoculated in the early part of the year, at the time 

 when smallpox prevailed, and the practice they used was to moisten 

 with water a bit of cotton wool prepared in the previous outbreak, to 

 place it on the arm of the person to be inoculated, and to prick the arm, 

 through the wool, over an area of about the size of a twenty-five cent 

 piece. In a few days a vesicle would appear at the seat of the inocula- 

 tion, which later on developed into a pustule and eruption. Notwith- 

 standing these precautions, great variation in the results was observed, 

 and many succumbed to the operation; but those that passed through it 

 safely were proof against further attacks. 



Besides the personal risk to the inoculated, the illness produced 



