Francis E. Lloyd — 150 — Carnivorous Plants 



blade with mere stumps of tentacles, (2) such pieces, or short pieces 

 of tentacle stalk placed for some time in a slightly hypotonic solu- 

 tion of cane sugar, remaining a few days to allow the putative sub- 

 stance to escape by diffusion; (j) young, still unfolded leaf tentacles, 

 the glands being removed and {4) a young but fully unfolded leaf 

 plunged into ethyl alcohol (96%) for 4-6 seconds. The alcohol be- 

 cause of the relative penetrabihty of the cuticles could not penetrate 

 into the leaf beyond the glands so that living tentacles with dead 

 glands were provided. Various difficulties involved need not be re- 

 cited here. 



On testing the responses of thus prepared material to a " stimulat- 

 ing" substance in the presence and absence of gland-extract, it was 

 found that, with few exceptions, aggregation did not occur in the 

 presence of either alone, but only when both were presented together. 

 As control the author used extracts of Drosera leafstalks, with negative 

 results. 



CoELiNGH also suspected that the aggregation-promoting substance 

 may occur also in the capital cells of other glandular structures of 

 Drosera since by the use of a stimulant (such as pepsin) she found it 

 possible to get aggregation in stalk cells of sessile and other glandular 

 trichomes and in leaf blade cells, even on the lower surface opposite 

 the bases of tentacles. On the other hand she could never obtain ag- 

 gregation in other parts of the plant where tentacles do not occur: 

 petals, sepals, ovary-wall, adventitious roots, young stipules. 



It was found also that there are substances (saliva, diastase, tryp- 

 sin) which act as the theoretical aggregation-promoting substance, 

 and in a search for a possible clue as to its nature, some such sub- 

 stances were tested on '^ empty" tissues. Saliva added to pepsin acts 

 positively, even after heating to exclude enzymes, but saliva also acts 

 alone, as I have found. The composition of saHva being known, the 

 various components were tried and only the phosphates were active. 

 For example a 0.1% solution of Na2HP04 was active and sahva di- 

 luted to this concentration of that salt was also. Aggregation follows 

 on the use of pepsin plus growth-substance of Indian corn on "empty" 

 pieces of tentacle, while pepsin or meat-extract alone have no effect. 

 Among organic N-substances, aspartic acid, asparagin and leucine have 

 the greatest action; creatin, alanine and urea are doubtful or negative; 

 guanine and ethylurethane no effect whatever. Substances which 

 lower surface tension (saponin, amylalcohol) have no effect. The 

 presence of oxygen, as Darwin had found, is necessary. Since the 

 swelling of protoplasm is considered characteristic of aggregation, per- 

 haps the chief one (Schimper), it was thought that the pB. of the ag- 

 gregating agents would betray an influence, but on experimentation 

 only negative results were obtained. 



CoELiNGH in a discussion of all the facts observed fully agrees with 

 Akerman, that two substances are needed to procure aggregation: 

 i) one with property A, which does not cause aggregation, but which 

 conditions cells to aggregate; and 2) one with B, which provides a 

 stimulus (pepsin, etc.) to aggregation. But it may not be assumed that 

 all substances have only one of these properties A and B but not both, 

 for some may have both in various degrees of efficiency. This is indi- 



