32-i DARWINIANA. 



these little sacs, hanging from submerged leaves or 

 branches, have their orifice closed by a lid which opens 

 inwardly a veritable trap-door. It had been noticed 

 in England and France that they contained minute 

 crustacean animals. Early in the summer of 1874, 

 Mr. Darwin ascertained the mechanism for their capt- 

 ure and the great success with which it is used. But 

 before his account was written out, Prof. Cohn pub- 

 lished an excellent paper on the subject in Germany ; 

 and -Mrs. Treat, of Yineland, New Jersey, a still ear- 

 lier one in this country in the New York Tribune in 

 the autumn of 1874. Of the latter, Mr. Darwin re- 

 marks that she "has been more successful than any 

 other observer in witnessing the actual entrance of 

 these minute creatures." They never come out, but 

 soon perish in their prison, which receives a continued 

 succession of victims, but little, if any, fresh air to the 

 contained water. The action of the trap is purely me- 

 chanical, without evident irritability in the opening or 

 shutting. There is no evidence nor much likelihood of 

 proper digestion ; indeed, Mr. Darwin found evidence 

 to the contrary. But the more or less decomposed 

 and dissolved animal matter is doubtless absorbed in- 

 to the plant ; for the whole interior of the sac is lined 

 with peculiar, elongated and four-armed very thin- 

 walled processes, which contain active protoplasm, and 

 which were proved by experiment to " have the power 

 of absorbing matter from weak solutions of certain 

 salts of ammonia and urea, and from a putrid infusion 

 of raw meat." 



Although the bladderworts "prey on garbage," 

 their terrestrial relatives "live cleanly," as nobler 



