92 



While it is possible to observe in a short time all the facts re- 

 lated above we must remember that it is the work of many men 

 that has taught us to observe the traps and correctly to interpret 

 our observations. 



The earlier investigators failed to grasp the significance of the 

 bladders. Thus we find that the Crouan brothers (1858) thought 

 them protective devices and regarded the quadrifid hairs as root- 

 hairs. To others the bladders were flotation organs and Darwin 

 (1875) occupied himself for a while in disproving that possibility. 



Xo fewer than four people, as Skutch (1928) reminds us in 

 a recent review, discovered independently that the trap is an active 

 mechanism. These were Brocher of Belgium (1911), Ekambaram 

 in India (1916), Withycombe in England in the same year and 

 lastly Hegner in the New Yorld in 1925. Darwin himself more 

 than fifty years ago came within a hairsbreadth of making the 

 same discovery ! 



The catholic taste displayed by Utrlciilaria has intrigued many 

 and the literature is full of references to the variety of organisms 

 trapped. Among the most interesting observations in this field 

 are those of Goebel (1889) and it will be not inappropriate to 

 select one from the many. Utricularia intermedia and U. vulgaris 

 when grown together caught quite different animals, the former 

 securing Cypris, the latter Copepods. Goebel connected these 

 facts with the observation that Cypris is a creeping form and is 

 therefore more likely to meet with the rooted U. intermedia, 

 while the freely floating U. vulgaris is well situated to trap the 

 swimming copepods. 



Hegner (1926) records the capture of Paramoecia : we on the 

 other hand, have not seen this with Utricularia gibba. This may 

 be due to some slight differences that prevent our plants from 

 trapping Paramoecia. He would be a brave man, though, who 

 would draw any conclusions from the negative results of observa- 

 tion for no less than seventy-five years of observation passed be- 

 fore Lloyd recorded the veil which seems to seal the door, and it 

 was but twenty years ago that Brocher observed the springing of a 

 trap! 



We might speculate along a dozen lines without exhausting the 

 field. We know nothing of the method by which water is pumped 

 out of the traps. What are the digestive enzymes of the bladders 



