300 PINGUICULA VULGARIS. [Chap. XVI. 



plant. The sixteen seeds belonged to nine difTorent kinds, which 

 could not be recognised, excepting one of Ranunculus, and several 

 belonging to three or four distinct species of Carex. It apjK'ars 

 that fewer insects are caught late in the year than earlier; thus in 

 Cumberland from twenty to twenty-four insects were observed in 

 the middle of July on several leaves, whereas in the beginning of 

 September the average number was only 2.27. Most of the insects, 

 in all the foregoing cases, were Diptera, but with many minute 

 Hymenoptera, including some ants, a few small Coleoptera, larvae, 

 spiders, and even small moths. 



We thus see that numerous insects and other objects are 

 caught by the viscid leaves; but we have no right to infer 

 from this fact that the habit is beneficial to the plant, any 

 more than in the before-given case of the Mirabilis, or of 

 the horse-chestnut. But it will presently be seen that dead 

 insects and other nitrogenous bodies excite the glands to 

 increased secretion; and that the secretion then becomes 

 acid and has the power of digesting animal substances, such 

 as albumen, fibrin, &c. Moreover, the dissolved nitrogenous 

 matter is absorbed by the glands, as shown by their limpid 

 contents being aggregated into slowly moving granular 

 masses of protoplasm. The same results follow when insects 

 are naturally captured, and as the plant lives in poor soil and 

 has small roots, there can be no doubt that it profits by its 

 power of digesting and absorbing matter from the prey 

 which it habitually captures in such large numbers. It will, 

 however, be convenient first to describe the movements of 

 the leaves. 



Movements of the Leaves. That such thick, large leaves 

 as those of Pinguicula vulgaris should have the power of 

 curving inwards when excited has never even been suspected. 

 It is necessary to select for experiment leaves with their 

 glands secreting freely, and which have been prevented from 

 capturing many insects; as old leaves, at least those grow- 

 ing in a state of nature, have their margins already curled 

 so much inwards that they exhibit little power of movement, 

 or move very slowly. I will first give in detail the more 

 important experiments which were tried, and then make 

 some concluding remarks. 



ETperiment 1. A young and almost upright leaf was selected, 

 with its two lateral edges equally and very slightly incurved. A 

 row of small flies was placed along one margin. When looked at 



