86 THE GERM THEORY OF DISEASE. 



be the physiological fact in the case, only Mr. Lister seems 

 not to have reached the point of recognizing the general phy- 

 siological law appertaining to this subject. 



I should explain the phenomena in this wise ; the soluble 

 ferment, diastase, or digestive agent given out by this bacteri- 

 um, must attain to a certain degree of intensity, or concentra- 

 tion, before it is capable of acting on blood serum. A single 

 bacterium is incapable of forming a sufficient quantity of 

 soluble ferment, when dissipated among the serum, to accom- 

 plish this digestion, and being incapable of appropriating the 

 undigested material, dies of dyspepsia; while, if a large num- 

 ber are massed together, there is a corresponding concentration 

 of the ferment substance, the digestion of the serum is accom- 

 plished, and the colony will flourish. The serum is speedily 

 decomposed. 



The soluble ferment of B. termo has been practically 

 demonstrated by Wortnian, who has shown that starch may 

 be remoleculized by this organism if no other source of car- 

 bon is available. And that in this case a diastase (soluble 

 ferment) is secreted which first transforms the starch into 

 sugar (glucose), which is consumed by the bacteria as fast as 

 formed. If a potato be boiled and a slice cut from it smoothly, 

 to expose the surface, and this surface be exposed to the air 

 for a few minutes, in order that a few germs that may be 

 floating in the air may light upon it, and this be protected 

 afterwards from other germs by a bell-glass covering, with 

 sufficient water to prevent drying, there will be a develop- 

 ment of clusters of bacteria lying upon the surface. In or- 

 dinary summer temperature this may be seen, usually, after 

 two or three days, as small points of varying colors. Now, 

 if these points be removed, one by one, and examined with 

 the aid of a microscope, it will be found that each little cluster 

 is, as a rule, made up of micro-organisms of one distinct 



