OF THE HUMAN SKIN. 59 



difficulty that fungous mould can he prevented from 

 germinating: for instance, in or on vegetable and 

 animal substances. Every one knows how soon 

 dampness produces mould. Now the vegetable 

 parasites of the skin are, as we said, one or sev- 

 eral species of fungi. So constant is the presence 

 of spores in nature, that it has really become more 

 difficult to explain why more do not germinate on 

 our bodies than why any do. A certain and steady 

 degree of warmth and moisture are requisite for 

 the development of vegetable life. Besides this 

 is needed rest and quiet of the seed, that it may 

 take in its nourishment from the surrounding me- 

 dium. Your inkstand will have no mould on it if 

 it is in daily use. The same with your jars of 

 preserves and pickles. A well-raked garden-path 

 has no weeds, as also a well-tilled field. The 

 reason why the vegetable spores do not germinate 

 more often on the living body is, that the body's 

 growth and constant change of tissue^ throwing off 

 of old to be replaced by new, interferes witli their 

 opportunity. Warmth aud moisture are present, 

 but the third element requisite to development is 

 wanting; namely, a quiet resting-place. Hence 

 we readily see that the more we use soap aud 



