278 Dr. Edward E. Klein [Feb. 20, 



AltliOTigli tlie notion that all epidemic diseases are communicable, 

 i. e. spread from one individual to another, is not a new one, since 

 many writers of former generations have had clear ideas about them, 

 yet the actual demonstration of the fact that the diiferent infectious 

 or communicable diseases are due to definite species of microbes, 

 which, having invaded a human or animal organism, are capable 

 therein of multiplying and of causing a particular infectious illness ; 

 further, the identification of these living germs in the blood and tissues 

 of an invaded individual, and the recognition of their many and intricate 

 migrations outside the animal body ; the study of the microbes in 

 artificial cultures, i. e. outside the human or animal body ; further, 

 the best means to do battle with them, to neutralise them, to prevent 

 their growth and to destroy them ; then the modus operandi of the 

 differen*t species, each appertaining to, and causing, a definite kind 

 of disorder — in short, all that is exact and precise in the knowledge of 

 the causation, nature, and prevention of infectious diseases, is an out- 

 come of investigations carried on during the last twenty-five years. 

 Modern research has not only definitely demonstrated these microbes, 

 it has also shown that a number of diseases not previously suspected 

 as communicable have a similar cause to the above, and are therefore 

 now classed amongst them. It need hardly be emphasised that a 

 knowledge of the causes must lead, and as a matter of fact has led, 

 to a clearer and better understanding of the recognition, prevention, 

 and treatment of these disorders, an understanding obviously directed 

 towards, and followed by, the alleviation and diminution of disease 

 and death in man and animals. 



I may point to a few special examples to illustrate these proposi- 

 tions. The disease known as splenic apoplexy or malignant anthrax 

 is a disease affecting man and brutes. In some countries the losses 

 to agriculturists and farmers owing to the fatal character of the disease 

 in sheep and cattle is enormous. In man it is chiefly known amongst 

 wool-sorters and those engaged in the handling of hides. This disease 

 has been definitely proved to be due to a bacillus, the Bacillus 

 anthracis, which, after its entry into the system of an animal or 

 human being, multiplies very rapidly in the blood and spleen, and, 

 as a rule, produces a fatal result, at any rate in sheep and cattle. 

 Now, the bacillus having been proved to be always associated with 

 this disease, anthrax, it was then shown that this bacillus can grow 

 and multiply also outside the animal body : its characters in artificial 

 media have been carefully studied and noted, so that it can be easily 

 recognised ; and by the pure cultures of the bacillus the disease can 

 be again reproduced in a suitable animal. Such cultures have been 

 subjected to a number of experiments with heat, chemicals, or anti- 

 septics ; the chemical function of the Bacillus anthracis has been and 

 is being accurately studied in order to give us an insight into the 

 mode in which it is capable of producing the disease ; it has been 

 further shown by Koch that the bacilli are capable of forming seeds 

 or spores which possess a very high degree of resistance to various 



