INFLUENCE OF ENVIRONMENT ON PLANTS 341 
saprophytes. Their mode of nutrition is, however, essen- 
tially the same. They have 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 
Ss 
Fic. 145.—Thesium alpinum, 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 hyphe, which 
ramify in the nutrient substratum, either living or dead, 
and which absorb elaborated products of some complexity 
