Francis E. Lloyd — 136 — Carnivorous Plants 



specting some of the contracted leaves we observed a small insect or 

 fly very closely imprisoned therein, which occasioned some astonish- 

 ment as to how it happened to get into so confined a situation. After- 

 wards, on Mr. Whately's centrically pressing with a pin other leaves 

 which were yet in their natural and expanded form, we observed a 

 remarkable sudden and elastic spring of the leaves, so as to be inverted 

 upwards and, as it were, encircling the pin, which evidently showed the 

 method by which the fly came into its embarrassing position." 

 (Withering 1796). It is unfortunate that Dr. Whately did not 

 record his observations himself since the rate of movement seems, by a 

 trick of memory, to have been exaggerated by the writer, Mr. Gardom. 

 As late as 1855 the facts were denied by Trecul, but in i860 Nitschke 

 made a thoroughgoing study, substantiating the earlier observations, 

 to be followed by Darwin, who had been heralded both by Hooker 

 and by Asa Gray, to whom Darwin had previously communicated 

 his results. Of 267 pages of Darwin's book on Insectivorous Plants 

 230 are devoted to an extraordinarily minute examination of the activ- 

 ities of Drosera, attesting to his immense patience and determination 

 to uncover every secret possible. 



Following Darwin various trends of investigation can be followed. 

 His observation of the phenomenon of aggregation was the beginning 

 of numerous studies of the cytological changes in glandular and other 

 cells, summarized by Homes. Other trends have been in the field of 

 anatomy, already discusssed, of digestion and nutrition and of the 

 nature of the movements, all to be duly considered. 



Mucilage. — While the papillae have not been observed to throw 

 off secretion, unless it be water (Konopka), the glands of the tentacles 

 are very conspicuous because each bears a drop of mucilage of high 

 viscidity, clear and ghstening, secreted by and supported on it (ij — 9). 

 The glands are charged with red pigment, so that the shining drops of 

 mucilage lend to the leaf a brilliant red hue. Since these persist as 

 well during the sunshine as otherwhile, we have the name "sundew" 

 common among Europeans. This mucilage, because of its briUiance 

 and reflected color, may be interpreted as a visible lure; it is at all 

 events an effective means of capturing prey of small dimensions, if it 

 ventures to alight on the glands. A delicate fungus-like odor which 

 has been detected by various observers (Geddes) may be an additional 

 factor of allure. The insect caught is soon (Nitschke: 15 min.) wet 

 all over and smothered by the secretion, which upon stimulation is said 

 to flow more freely. Darwin investigated the secretion activity on 

 the application of various kinds of substances and found that not only 

 does the secretion increase in the gland directly stimulated, but in 

 nearby glands as well, as the result of transmitted stimulus. When 

 the stimulating material is nitrogenous the secretion becomes acid, sup- 

 plying an important condition for digestion. The amount of secretion 

 which becomes applied to the captured prey is increased not only by a 

 more ample supply of secretion, but by the movement of the tentacles 

 which bring more glands than originally stimulated into contact with 

 the prey. The secretion, Darwin showed, is possessed of antiseptic 

 properties, and thus inhibits the action of bacteria. In his experiments 

 he found that bits of meat and of albumen placed on the Drosera leaf 



