348 VEGETABLE PHYSIOLOGY 
the parasitic habit is associated with a degeneration of 
structure, which especially affects the vegetative organs. 
The fungus which is parasitic in habit derives all its 
nourishment from the plant or animal whose tissues it has 
invaded. Other plants of the same group are not parasitic, 
but live upon decomposing organic matter, bemg known 
as saprophytes. Their mode of nutrition is, however, 
essentially the same. They have all lost the chlorophyll 
apparatus characteristic of the green plant, and cannot 
SSS SSS 
Fia. 145.—Thesium alpinum, SHOWING THE SucKERS ON THE Roors. 
(After Kerner.) 
therefore work up the food materials that the latter absorbs 
from the air. Instead, therefore, of absorbing carbon 
dioxide, these plants take in their carbohydrate food ready 
made 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 pre- 
ference to nitrates. No doubt their protoplasm is ultimately 
fed with the same substances as is that of the higher plants, 
