fee ted cows, which he transferred into the skin of humans. 

 Upon later introduction of smallpox extracts into these 

 people, no disease resulted. Jenner, although ignorant of 

 the existence of the smallpox virus, was thus able to de- 

 velop the first effective technique of immunization of hu- 

 man beings against a disease. 



The introduction of aseptic techniques of surgery dur- 

 ing the last century (Lister, 1865), using disinfectants such 

 as carbolic acid, greatly reduced the mortality rate due 

 to gangrene (bacterial infection of wounds), and the dis- 

 covery of ether as an anaesthetic (Morton, 1846) made 

 surgery approach something like a scientific discipline — 

 the anaesthetized patient could now be operated upon with- 

 out the terrible pain previously resulting, and in a condi- 

 tion of relaxed muscles enabling the surgeon to work with 

 comparative ease and at an unhurried pace. Later, im- 

 proved anaesthetics like pentothal, injected intravenously 

 to produce anaesthesia within a few seconds of adminis- 

 tration, followed by ether and oxygen, made operations not 

 unpleasant (post-operative pain being minimized with mor- 

 phine). Local operations could be done under the influ- 

 ence of a local injection of procaine. 



The discovery of the existence of different human blood 

 groups, mutually incompatible in transfusion between indi- 

 viduals (Landsteiner, 1901), was a major step forward in 

 medicine. Now it became possible to transfer blood from 

 healthy individuals to those suffering from loss of blood 

 (either through accident, or during surgery), with cer- 

 tainty of success. Today intense study of the blood is be- 

 ing carried out to determine the causes for its abnormal 

 clotting behavior in thrombosis, and to investigate the 

 whole mechanism of immunity, afresh. 



With Pasteur's work on bacteria, followed by that of 



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