624 PHARMACEUTICAL BOTANY 
elongated. They secrete, absorb and are acted upon by various: 
stimulants. 
Darwin! has shown that when a small object is placed on the 
tentacles in the center of the leaf these transmit an impulse to the 
marginal tentacles. The nearer ones first respond and slowly 
bend toward the center and then those farther away until finally 
all become bent over the object. The time essential varies from 
10 seconds to 5 or more hours depending upon the nature, con- 
tents and size of the object, upon temperature and also upon the 
age of the leaf. Again, if the glands are repeatedly touched or 
brushed or if chemical substances are placed on these, the mar- 
ginal tentacles curve inward. The bending part of each tentacle 
is confined to a limited space near the base. Not only the ten- 
tacles but the blade of the leaf becomes much incurved when any 
strongly exciting substance is placed on the blade. 
The time during which the tentacles and blade remain curved 
over the object varies according to the temperature, character of 
object, age, etc. Dr. Nitschke? found that during cold weather — 
both the blades and tentacles re-expand within a shorter period 
than when the weather is warm. Darwin* found that the ten- 
tacles remain clasped for a much longer period over objects 
which yield soluble nitrogenous matter than over those yielding 
no such matter. After a period varying from 1 to 7 days the 
tentacles and blade re-expand and are then ready to again 
respond. It has been shown by the same authority that as soon 
as the tentacles become inflected over an object yielding soluble 
nitrogenous matter their glands pour out an increased amount 
of secretion which becomes acid in nature. These glands, more- 
over, continue to secrete as long as the tentacles remain closely 
inflected. 
In nature small insects catch sight of the glittering drops on 
the tips of the reddish tentacles and, mistaking these for honey, 
alight upon the leaf. They become instantly entangled by the 
viscid glandular secretion. They try to stroke the viscid fluid off 
of their legs but only besmear themselves more. Soon they 
' Darwin: Insectivorous Plants, p. 9, 1884. 
* Darwin: Insectivorous Plants, p. 13, 1884. 
* Darwin: Insectivorous Plants, p- 13, 1884. 
