INFLUENCE OF ENVIRONMENT ON PLANTS 341 



saprophytes. Their mode of nutrition is, however, essen- 

 tially the same. They hare all lost the chlorophyll 

 apparatus characteristic of the green plant, and cannot 

 therefore work up the food materials that the latter 

 absorbs from the air. Instead, therefore, of absorbing their 

 carbon in the form of carbon dioxide, these plants take it 

 in in the form of an organic compound of some complexity, 

 which is usually some kind of sugar. Saprophytes can 

 absorb nitrogen in the same combinations as a green 

 plant, but they appear to utilise compounds of ammonia in 



FIG. 145. Thfsiuin alpininn, SHOWING THE SUCKERS ON THE ROOTS. 

 (After Kerner.) 



preference to nitrates. No doubt their protoplasm is 

 ultimately fed with the same substances as is that of the 

 higher plants, but they lack a great deal of the constructive 

 power of the latter. 



The degradation of the structure of such plants is 

 associated with the absence of the constructive processes 

 which depend on the presence of chlorophyll. Their body 

 is usually composed chiefly of delicate hyphee, which 

 ramify in the nutrient substratum, either living or dead, 

 and which absorb elaborated products of some complexity 



