176 THERAPEUTICS AND PHARMACOLOGY 



the interior of the body, although it may sometimes be used, as for 

 example in the treatment of dysentery, where repeated doses of 

 saline purgative are now given so as to wash out from the intestinal 

 canal the microbes which give rise to the disease, and even in ordinary 

 diarrhea, where a purgative is employed to get rid of both the 

 microbes and the poisons they have formed. More commonly, how- 

 ever, we have to depend on antiseptic methods either entirely or as 

 an adjunct to asepsis, and a study of the action of various chemical 

 substances on microbes has led to the introduction of a whole series 

 of antiseptics and indeed to their actual synthetic formation, the 

 problem to be solved being how to produce a body which will de- 

 stroy the microbes most efficiently and at the same time will have 

 the least injurious action upon the body of the animal invaded. Nor 

 is it only inside the body that the action of antiseptics is desired. 

 The search for preservatives for milk, meat, fish, vegetables, and fruit 

 which shall be at the same time efficient and innocuous is one con- 

 stantly going on at present. Asepsis is one of nature's methods of 

 defense. When irritating substances get into the eye a flow of tears 

 occurs to wash them away, from the nose and respiratory passages 

 they are ejected by sneezing or by cough, and from the stomach or 

 intestines they are removed by the vomiting and purging to which 

 they themselves give rise. Even in the addition of preservatives in 

 milk we seem to be following the example of nature because Andeer 

 has found resorcin in which is an antiseptic in the fresh milk of cows. 

 As Metchnikoff has shown, another method adopted by nature for 

 removing and destroying infective microbes is to bring down upon 

 them a host of white blood corpuscles, or leucocytes, which swallow 

 up and destroy them. The more leucocytes that the organism can 

 bring to bear upon the intruders the better chance it has of over- 

 coming them. One problem, therefore, in therapeutics is to increase 

 leucocytosis. At present we have comparatively few drugs that pos- 

 sess this power, cinnamate of sodium being perhaps the most active, 

 but one of the problems to be solved is to find other substances which 

 will do this to a greater extent than at present. The microbes on their 

 part are ready to attack the leucocytes and fixed cells by means of 

 toxic secretions or toxins and another of the defensive mechanisms 

 which the organism adopts is to form antitoxins, as the antitodes to 

 these toxins are generally termed. Some of these defensive bodies 

 or alexins actually destroy the invading microbes themselves, while 

 others simply neutralize the poisons or toxins they have formed. 

 The nature of such defensive substances has been examined by 

 Ehrlich to whom we owe much of our knowledge concerning them. 

 It is very complicated and we do not yet know the precise mode of 

 production of these antitoxins, but it is a curious fact that in many 

 plants we find two poisons which are antagonistic in their action and 



