PINGUICULA. 173 



inflict on the reader in detail. The plants almost inva- 

 riably attempted to digest everything placed on their 

 leaves, but the results were very different. Substances 

 from which they could obtain no nourishment caused 

 but a slight secretion, while all soft-bodied insects and 

 bits of fresh meat caused abundant secretion. And even 

 with digestible substances there was often quite a differ- 

 ence in the time it took to dispose of the same things. 

 Some days the secretion was much more copious than 

 others. This puzzled me for a time, until I found that 

 on rainy days insects placed on the freshest leaves ex- 

 cited but little secretion. The drier the atmosphere, 

 the better the plants worked. So I found by these 

 experiments that I had a vegetable barometer, and that 

 there was no danger of rain when the plants secreted 

 abundantly. 



^The movement of the leaf is still a puzzle to me. 

 Some leaves folded so that the two edges met over the 

 prey, while others on the same plant that secreted and 

 digested equally well made no movement. 



