2 MacDougaL — Symbiotic Saprophytism. 
customary to designate all species that have lost the chloro- 
phyll-apparatus as holosaprophytes ; and all those which 
show only a slight degeneration of the structures mentioned 
above, as hemisaprophytes. As a matter of physiological 
fact, the hemisaprophytes are not sharply separated from 
the autophytes, since all of the latter class are in a sense 
hemisaprophytic. 
The acquisition of complex compounds by the higher 
plants may be accomplished by three methods. In one 
the limiting membranes of the absorbing organs are modified 
to permit the passage of organic food-substances. Complete 
saprophytism by this method has been accomplished by one 
species only, W ullschlaegelia aphylla , a colourless Orchid of 
the West Indies, according to Johow’s investigations. In my 
own work upon the subject it has been demonstrated that 
this capacity is shared by Cephalanthera oregana , a waxy 
white plant from western North America. 
The second method of saprophytism is that by which the 
‘ carnivorous ’ plants entrap and receive the bodies of plants 
and animals in differentiated portions of the shoot, and take 
up the products of their decomposition by means of specialized 
absorbing cells. About six hundred carnivorous species are 
known, and while the material obtained in this way is 
beneficial to the plant, it is not absolutely necessary to its 
existence or normal development. It follows quite naturally 
that no species has attained complete saprophytism by this 
method. 
By a third method the higher plant gains complex sub- 
stances through the agency of Fungi interposed between 
its own protoplasts and the nutritive substratum. The fungal 
hyphae may replace the external layers of the underground 
absorbing Organs, may occupy these layers, or may penetrate 
into the cortex either between or through the cells. In any 
case the arrangement is such as to interpose the walls of 
the Fungus alone between the nutritive medium and the 
protoplasts of the higher plant. The walls of the Fungus 
have developed a capacity for the osmotic passage of organic 
