IS THE VALVE OF UTRICULARIA SENSITIVE? 147 



Chapter IX. 



IS THE VALVE OP UTRICULARIA SENSITIVE? 



After the observations were made which are record- 

 ed in the last chapter, I continued my studies for several 

 months on different species of Utricularia, and during 

 this time Mr. Darwin's book on " Insectivorous Plants " 

 appeared. It is so comprehensive, and the experiments 

 have been so carefully conducted, that it seems pre- 

 sumptuous for any to attempt to differ in the least 

 from his conclusions; and in. the main a careful experi- 

 menter must agree with him. But there are a few of 

 the points which he has treated in his chapter on Utric- 

 ularia in regard to which my observations and experi- 

 ments have led me to conclusions somewhat different 

 from his. 



The species that I most closely observed were Utricu- 

 la/ria inflata, U. vulgaris, U. clandestina, U. intermedia, 

 U. striata, U. gibla, U. purpurea, U. cornuta, and U. sub- 

 ulata. Most of these species vary slightly, and a few 

 considerably, in the construction of the utricle. I have 

 selected for illustration two of the most widely dissim- 

 ilar species that I have examined, U. inflata and U. pur- 

 purea. Fig. 5 represents a portion of U. inflata, re- 



