134 THE GERM THEORY OF DISEASE. 



been isolated, as the toxic elements of the waste products of 

 animal life have been isolated, and as, through this isolation, 

 the exact properties of these agents have become known to 

 us, so must sepsin be isolated, so must the poisonous product 

 of the bacillus anthracis (Anthracine) be isolated, so! must 

 the poisonous principle of every disease-producing germ be 

 isolated, and each of these studied separate and apart from 

 the organisms which produce them ; and in each case their 

 properties must be demonstrated and determined by direct 

 experiment, before they can be said to have been accurately 

 studied, and that we know their properties and capabilities. 

 This is the recognized means of learning the powers and 

 capabilities of the products of the higher plants and animals. 

 No one is foolish enough to deny the value, the necessity, of 

 the knowledge to be gained by this mode of study in the 

 vegetable kingdom. If there has been any truth arrived at 

 in all the research that has been given to the subject of the 

 production of disease by the lower organisms, that truth 

 requires to be extended, and rendered more exact, by the 

 modes of study we have just indicated. 



PHYSIOLOGICAL CHANGES. 



The question, as to whether the nature of the bacteria and 

 their allied forms are always essentially the same, is one that is 

 very important to determine. Very many persons seem to think 

 that the characteristics of this or that organism may be perma- 

 nently changed, by temporary changes in the media in which it is 

 grown. This is a question of the gravest importance ; and one 

 on which there has, as yet, been very little or no exact experi- 

 ment. Therefore we have nothing but conjecture ; unless, 

 indeed, we may regard the experiments of Pasteur, in his 

 efforts to moderate the virulence of the bacillus anthracis, the 

 organism of chicken cholera, etc., experiments in this direction. 



