PLANT NUTRITION. 33 
the supply of oxygen ‘to the ferment, in consequence of 
which the glucose they contain becomes converted into 
alcohol. 
Carnivorous Plants, Parasites,—The leaves of certain 
plants are endowed under certain circumstances with a 
power of digesting and absorbing animal substances 
placed in contact with them. When a minute fragment 
of meat, for instance, is placed upon the leaf of a drosera, 
or sundew, the tentacle-like glandular hairs of the plant 
bend over to grasp the intruding morsel, a peculiar di- 
gestive fluid is formed as a result of the contact—just as 
the gastric juice in the human stomach is secreted when 
food enters that organ—and this fluid effects the solution 
of the meat, the nutritive solution so formed being 
absorbed and applied to the benefit of the plant. To 
common observation the actual gain to the plant by this 
-method of feeding may appear slight, or even none ; but 
the more delicate tests applied by the botanist have 
sufficed to prove, not only that the processes just 
mentioned really do go on, but also that they are ben- 
eficial to the plant, and contribute to the formation of 
more numerous and more robust seedlings. The ration- 
ale of this mode of obtaining nutrition seems somewhat 
analogous to that in the root, where also the acid fluid 
with which the celi-wall is permeated, when it comes 
into contact with the particles of soil, determines their 
solution and renders them fit for absorption into the 
plant. Practically this admittedly exceptional mode of 
nutrition by the leaf might seem of little moment, but it 
is probable that in the future direct nutrition by this 
means will be shown to be of much greater importauce 
than it appears to be at present. In any case, the fact 
that ammonia-solutions and ammonia-vapors are absorbed. 
by leaves with increased manifestations of vital activity, 
renders this mode of feeding a matter of some conse- 
