Francis E. Lloyd — 180 — Carnivorous Plants 



In 1834 M. A. Curtis (quoted on p. 177), a minister resident in Wil- 

 mington, N. C, published his observations, which led him to think 

 that the sensitiveness resides only in the hair-like processes, and 

 that other parts of the leaf may be touched or pressed without any 

 response. This is not quite true, as has later been found. Further, 

 that insects captured are not always crushed on being caught, for 

 if the trap were opened again they might escape; but that in time 

 they were surrounded by a mucilaginous fluid by which the insects 

 were more or less consumed. The fact that a special sensitivity 

 resides in the six slender hairs of the upper surface of the trap had 

 been noted by a botanical draughtsman, Sydenham Edwards, em- 

 ployed by Dr. John Sims in illustrating Curtis's Botanical Magazine. 

 This observation was recorded by Sims (1804) in the description of plate 

 785 of vol. 20 which reads: "These small spines are mentioned and 

 figured by Ellis and supposed by him to assist in destroying the en- 

 trapped animal; but that they are only irritable points, and that any 

 other part of the leaf may be touched with impunity, was discovered 

 by our draughtsman, Mr. Edwards, several years ago, when taking a 

 sketch of a plant flowering at Mr. Lipman's, Mile End, and has since 

 been repeatedly confirmed. The same observation was made, without 

 knowing it had previously been noticed, by our friend Mr. Charles 

 Konig" (Hooker 1875). 



In 1859 OuDEMANS, a Dutch botanist, rediscovered the sensi- 

 tivity of the trigger hairs, and did a number of experiments which 

 afforded results which anticipated some of Darwin's. He found 

 that there is no periodic closure of the trap, as Meyen has claimed, 

 and that traps, after closure, opened again during the night. Meyen 

 had said that the closure was too slow to catch insects, to which 

 Oudemans answered that at sufficiently high temperatures it is rapid, 

 which we now know to be true. He recorded that the trap does 

 not open after catching prey until several days after its death. When 

 the trap does, the prey is found lying in a slimy liquid; and further 

 that the trap does not remain closed over inanimate objects such as 

 paper, reopening in 36 hours or less. Though he thought that the 

 stimulus was transmitted to the mid-vein, he attributed closure to 

 alterations of strain in the parenchyma. 



In 1868 Canby thought it might be that the fluids collecting 

 in the closed trap might escape and, flowing down the petioles of 

 the leaves, might enrich the soil at the base of the plant. Experi- 

 ments showed him, however, that this is not the case, but that, on 

 feeding the leaf, the insect is entirely destroyed and absorbed, thus 

 confirming Curtis, thirty-four years his predecessor. He concluded 

 by saying, "so that, in fine, the fluid (secreted by the leaves) may 

 well be said to be analogous to the gastric juice of animals,^ dissolv- 

 ing the prey and rendering it fit for absorption by the leaf." 



That, however, the sensitive hairs are the only sensitive spots 

 in the leaf was shown by Darwin and by Goebel (1891) not to be 

 true. "It is sufiicient to rub the upper or lower surface, and not 

 too strongly, with a solid object to procure immediate closure of the 

 two halves of the trap" (Goebel). This, as will be seen, has later 

 been confirmed. 



