GERMS. 2 1 



scanty supply derived by their power of breaking up complex 

 chemical compounds. 



These features will require more exact delineation in the section 

 upon the vital functions of micro-organisms. 



Germs. 



19. The features of micro-organisms thus far described have applied 

 only to their adult state. Up to the present, but little is known of 

 their germ stage, beyond the fact that their spores are present in 

 water and in soil in innumerable numbers, and are almost constantly 

 floating in the atmosphere as fine impalpable organic dust. Atmo- 

 spheric germs may even come to have a distinct qualitative value 

 of their own, — not, it is true, from any qualities which they at 

 present possess, beyond what may be summed up in the term 

 " vitality," but in potential properties, which may at any time become 

 active. These possibilities may be roughly gauged by the careful 

 observation of the atmosphere in which they float, as, for instance, 

 noting its hygroscopic conditions — a dry atmosphere being, as a rule, 

 less germ-laden than a saturated one — and such gross meteorological 

 observations as the direction and force of the wind, and the condition 

 of the earth's surface, whether dusty or otherwise. High winds and 

 dust tend to load the atmosphere with germs ; absence of wind and 

 rain have the opposite effect, allowing of mechanical subsidence of 

 the floating germs, and providing for their distribution in the soil by 

 the percolating streams of rain, which they perforce accompany. 

 But wherever they may be, they retain their capabilities of growth 

 and development through almost all circumstances short of absolute 

 dessication by heat, or the action of some other powerful germicide, 

 and are prepared to develop into their adult form whenever they are 

 supplied with the necessary conditions of warmth, moisture, and a 

 nutrient soil. The fact that these three factors are so typically present 

 in the case of a surgical wound, accompanied by the lowered vitality 

 of the tissues — also a point of great importance — has led to the 

 development of a special department in surgical practice ; and a 

 recognition of the fact that the human body lends such admirable 

 aid to their growth and development is the key to understanding the 



