Francis E. Lloyd —128— Carnivorous Plants 



Darwin and Rosenberg, saw that aggregation and granulation occur 

 in response to the entrance of various substances, but this is true of 

 the tentacles, also, and proves as much and as little in both cases. 

 To be sure it was thought that the papillae produce no secretion ex- 

 ternally escaping, and this has perhaps influenced the judgment. As 

 OuDMAN remarks, here also as in the case of tentacles quantitative 

 results had not been forthcoming. He therefore endeavored to supply 



these. 



Having first assured himself that the N- content of the leaves (of 

 Drosera capensis) under the circumstances under which he worked, is 

 nearly constant, Oudman then arranged a simple experiment (i) so 

 that the more marginal tentacles were surrounded by agar (2%), with 

 asparagin (1.5%), and (2) so that the mixture was poured on the back 

 of the leaf taking precautions against capillary flow. He obtained 

 these results : 



Treatment of the Leaf 



N IN % OF INCREASE IN 

 FRESH WEIGHT 24 HOURS 



From these figures it was evident that asparagin is taken up both 

 by the tentacles and by the back of the leaf. By comparing the total 

 area of the tentacle glands with that of the back of the leaf he found 

 that the amount of asparagin absorbed by the tentacles was six times 

 that absorbed by the back of the leaf. Two explanations presented 

 themselves, namely, either that the tentacle heads (glands) are better 

 adapted to this purpose than the leaf epidermis (which would be ruled 

 out by the fact that the epidermis is cuticularized, as above said); 

 or that the absorption by the leaf-back takes place only at certain 

 points, that is, through the papillae, through which it has been ob- 

 served that entrance can take place (Darwin, Rosenberg, Kok). 

 Oudman adopted the latter view, and inferred that in nature both the 

 tentacles and the papillae are made use of for the absorption of food, 

 but rather the papillae of the upper side of the leaf than those of the 

 lower. Oudman also examined into the question of the influence of 

 various factors (temperature, concentration of the applied materials, 

 the course of absorption in relation to time, the nature of the ap- 

 pHed material, the influence of the glands and narcosis). 



As would be expected, the higher the temperature within physio- 

 logical limits, the more rapid the absorption. But whether this is 

 due to the greater rapidity of transportation, or to the greater uptake 

 by the glands, does not appear. The same with increasing concentra- 

 tions of applied substance (asparagin). In the course of absorption, 

 the rate was greater after the first period (3-6 hrs.), than at first, and 

 falls off again after 9 hours. This, it may be suggested, may be due to 



