324 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 Vineland, 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 



