380 PINGUICULA VULGARIS. Chap. XYI. 



Prof. Dyer, in most or all the species of the genus, 

 the edges of the leaves are in some degree naturally 

 and permanently incurved. This incurvation serves, 

 as already shown, to prevent insects from being 

 washed away by the rain ; but it likewise serves for 

 another end. When a number of glands have been 

 powerfully excited by bits of meat, insects, or any other 

 stimulus, the secretion often trickles down the leaf, 

 and is caught by the incurved edges, instead of rolling 

 off and being lost. As it runs dovm. the channel, fresh 

 glands are able to absorb the animal matter held in 

 solution. Moreover, the secretion often collects in 

 little pools within the channel, or in the spoon-like 

 tips of the leaves ; and I ascertained that bits of albu- 

 men, fibrin, and gluten, are here dissolved more 

 quickly and completely than on the surface of the 

 leaf, where the secretion cannot accumulate ; and so 

 it would be with naturally caught insects. The'secre- 

 tion was repeatedly seen thus to collect on the leaves 

 of plants protected from the rain ; and with exposed 

 plants there would be still greater need of some pro- 

 vision to prevent, as far as possible, the secretion, with 

 its dissolved animal matter, being wholly lost. 



It has already been remarked that plants growing 

 in a state of nature have the margins of their leaves 

 much more strongly incurved than those grown in 

 pots and prevented from catching many insects. We 

 have seen that insects washed down by the rain from 

 all parts of the leaf often lodge within the margins, 

 which are thus excited to curl farther inwards; and 

 we may suspect that this action, many times repeated 

 during the life of the plant, leads to their permanent 

 and well-marked incurvation. I regret that this view 

 did not occur to me in time to test its truth. 



It may here be added, though not immediately 



