THE SUBTLETY OF LIFE. 



Bv MARC.ARIIT K. THOMSON. 



It has long been a matter of common knowledge 

 that certain organic poisons which gain an entrance, 

 by some means or other, into the human body, have 

 the effect, when once overcome by their victim, of 

 rendering him invulnerable, or " immune," so far 

 as that particular poison is concerned, usually for 

 the rest of his lifetime. Familiar instances are the 

 poisons produced by certain common infectious 

 diseases, measles, whooping-cough, scarlet fever and 

 the like, one attack of which, in the majority of 

 cases, has the effect of protecting from subsequent 

 attacks. It is on this fact of immunisation that 

 vaccination as a preventive for smallpo.x is based, 

 and the knowledge of it led Pasteur to his wonderful 

 results in the treatment of rabies and in the " taming " 

 of the deadly anthrax bacillus. 



Equallv familiar is the fact that there are poisons 

 which render the individual increasingly tolerant of 

 them if their use is persisted in. Thus, the con- 

 firmed opium-taker can imbibe or inject a dose which 

 would certainly be fatal to a normal individual, and 

 which would have been fatal to himself had he not 

 accustomed himself to gradually increasing quanti- 

 ties. De Quincey, in his " Confessions," tells us 

 that he gave to a wandering Malay who came to his 

 door, a piece of opium large enough to kill six 

 dragoons and their horses if they were not trained 

 to it. The Malay received it with delight, broke it 

 into three pieces, and immediately swallowed them all. 

 De puincey"s own allowance at one period of his 

 life was eight thousand drops of laudanum a day. 



Within the last seven or eight years a new aspect of 

 the effect of poisons has come into prominence. 

 Certain poisons when introduced into the circulation 

 increase, sometimes to an enormous extent, the 

 susceptibility of the individual to the toxic action of 

 that particular substance. This fact was apparently 

 not unknown to some of the earlier ph\siologists, 

 though it was not adequately described, and its 

 importance was not recognised. For all practical 

 purposes the phenomenon was discovered in 1902 

 by the eminent French physiologist. Professor Ch. 

 Richet, and he it was who coined for it the name 

 Anaphylaxis, — a companion word to prophylaxis or 

 protection against disease. 



In a recent number of a French journal. Professor 

 Richet himself describes the way in which he was 

 led to the discovery, and in the second edition of 

 his book* summarises the facts that have been 

 collected, and describes the experiments that have 

 been made by himself and by other physiologists in 

 various countries who have devoted their attention 

 to the subject. 



In the course of a series of experiments with the 

 poison from the " stinging cells " in the tentacle of 

 Actinia, one of the common sea-anemones, Professor 

 Richet soaked portions of the tentacles in glycerine. 



and injected the solution of the poison obtained into 

 the veins of a dog. He found to his great surprise 

 that, while for a fresh subject a fairly large dose was 

 required to cause death, a dog which had been 

 treated with the poison about a month previously 

 and had fully recovered his condition, quickly 

 succumbed to a dose of about one-twentieth the 

 original strength. That the poison was cumulative 

 in its effect was the most obvious explanation, but 

 the smallness of the dose, and the time which had 

 elapsed since the previous injection, showed that this 

 was improbable. The only possible conclusion from 

 this and other experiments was, that the first injection 

 brings about a particular physiological state which 

 makes the individual more sensitive to subsequent 

 injections. 



A further step was taken in 1903, when M. Arthus 

 showed that the same physiological state could be 

 induced by a substance, such as blood-serum, which 

 is not in itself toxic. .A rabbit, which had been 

 injected with a dose of horse-serum without showing 

 any signs of disturbance, a month later succumbed 

 at once on receiving an injection of one-twentieth 

 the quantity of the same material. 



Anaphylaxis is invariably specific — that is, an 

 animal rendered sensitive by previous injection to 

 one substance, is not affected as regards any other 

 substance, not even a different kind of blood-serum. 

 This has an interesting legal bearing. It supplies a 

 new and conclusive method of determining the 

 source of any given blood, e.^., whether it is human 

 or not. Thus if a set of guinea-pigs be treated with 

 the serum of different forms, man, dog, horse, and so 

 on — and after a month's interval be injected with a 

 solution of the blood to be identified, the relevant 

 guinea-pig will re-act at once, while the others will 

 remain unaffected. Quaint, too, is the experiment of 

 injecting an extract of the muscle of a human mummy 

 into a set of guinea-pigs — for here, as elsewhere, the 

 unfortunate guinea-pig has proved itself the best 

 subject for experiment, its sensitiveness to a special 

 substance being capable of being increased five- 

 thousand times — and after an interval injecting other 

 muscle-extracts. The animals re-acted to that of 

 human muscle, and to that alone, " thus proving, if 

 proof were needed, that the chemical constitution of 

 the human body has not notably varied in the last 

 three or four thousand years." 



The medical aspects of anaphylaxis are discussed 

 by Professor Richet in connection with the use of 

 tuberculin ; he regards the phenomenon as throwing 

 light on its diagnostic value, and probably also on 

 the occasional terrible accidents which for a time 

 almost discredited it as a therapeutic agent. This 

 latter point is still under investigation. The 

 " serum disease," too, which sometimes follows the 

 use of anti-toxin and inoculation for plague is 



" L' Anaphylaxie." Paris, 1912. 



