Now, these harmless serums become poisonous when they have been taken from animals which have been first treated with the blood or the organs of other species of animals. For instance, the blood serum of a sheep which has been treated with the blood of a rabbit becomes poisonous because it has acquired the power of dissolving the red blood corpuscles of the rabbit. It is a poison in the case of the rabbit, but is harmless to most other animals. The injection of the rabbit’s blood into the sheep has conferred on the sheep a new property which comes into operation only with regard to the red blood corpuscles of the rabbit. We have here to do with something analogous to what has been observed in the cases of serums used to arrest infectious disease. When the bacilli of diphtheria, or their products, have been injected into horses, there is produced an anti-diphtheric serum, capable of curing diphtheria, but powerless against tetanus or plague. After M. J. M. Bordet of the Pasteur Institute had made his discovery of serums that had acquired the power of dissolving the red blood corpuscles of other animals, the attempt was made to prepare similar serums directed against all the other elements of the body, such as white blood corpuscles, renal and nervous cells. In the course of these investigations it was proved to be necessary to employ a certain dose of the serum in order to obtain the poisonous result. If smaller quantities of the poisonous dose were used, the reverse effect was produced. Thus a serum, strong doses of which dissolved the red blood corpuscles and so made them less numerous in the blood, increased the number of these when given in very small doses.
M. Cantacuzène was the first to establish this fact in the case of the rabbit, whilst M. Besredka and I myself did it in the case of man.[117] Since then M. Bélonovsky of Cronstadt has confirmed the result on anæmic patients, treating them with small quantities of serum. He has been able to produce in them an increase in the number of the red blood corpuscles, and in the quantity of the red colouring matter (hæmoglobin) in the blood. Later on M. André[118] devoted much attention to this matter at Lyons. He prepared a serum by injecting human blood into animals and made use of it in the case of several persons who suffered from anæmia from different causes. In the case of patients, the anæmic condition of which had hitherto remained stationary, Dr. André found a sudden increase in the number of red corpuscles after injecting small doses of the serum. M. Besredka, in the case of laboratory animals, increased the number of white corpuscles by injecting them with a small quantity of a serum, strong doses of which destroyed these cells.
These facts are only a special case of the general rule that small doses of poisons increase the activity of the elements that are killed by large doses. In order to increase the activity of the heart, medical men give successfully small doses of cardiac poisons such as digitalis. As a commercial process, the activity of yeasts is increased by submitting them to weak doses of substances (fluoride of sodium) which, given in larger quantities, would kill them.
My general conclusion from these facts is that it is logical to lay down the principle that the higher elements of our body could be strengthened by subjecting them to the action of small doses of the appropriate cytotoxic serums. There is, however, much difficulty in putting this into practice. It is quite easy to obtain human blood to inject into animals with the object of preparing a serum which can increase the number of red corpuscles. On the other hand, it is extremely difficult to get human bodies sufficiently fresh to use them for a practical purpose. According to law, post mortem examinations can be made only after an interval of time in course of which the tissues have changed; besides, the organs obtained in this way are frequently affected by injuries or diseases militating against their use. Even in Paris, with its three million inhabitants, it is extremely rare that there is a good opportunity for the preparation of human cytotoxic serums. In two or three years, during which Dr. Weinberg has collected the organs from human bodies fairly fresh, he has been unable to obtain sufficiently active serums.
The best results have been obtained from new-born infants which have been killed by some accident in the process of child-birth, as in them the organs are in a normal state. However, owing to the advance in the practice of obstetrics, such accidents, already infrequent, are becoming extremely rare. In such conditions we may have to wait long before getting a positive result, unless the future will find some method of obtaining the necessary materials for this difficult and interesting purpose.
As it is so difficult to prepare a remedy which can strengthen the weakened higher elements of the body, it may be easier to find a means of preventing the weakening which interferes so much with our desire to live long. As the products of microbes are the most active agents in deteriorating our tissues, we must look towards them for the solution of the problem.
IV
INTESTINAL PUTREFACTION SHORTENS LIFE
Uselessness of the large intestine in man—Case of a woman whose large intestine was inactive for six months—Another case where the greater part of the large intestine was completely shut off—Attempts to disinfect the contents of the large intestine—Prolonged mastication as a means of preventing intestinal putrefaction