1843^862] DROSERA 267 



hair which caused movement and weighed -rs^m of a grain ; Letter 597 



but I do not believe it is weight, 1 and what it is, I cannot 



after many experiments conjecture. The movement in this 



case does not depend on the chemical nature of substance. 



Latterly I have tried experiments on single glands, and a 



microscopical atom of raw meat causes such rapid movement 



that I could see it move like hand of clock. In this case 



it is the nature of the object. It is wonderful the rapidity of 



the absorption : in ten seconds weak solution of carbonate of 



ammonia changes not the colour, but the state of contents 



within the glands. In two minutes thirty seconds juice of 



meat has been absorbed by gland and passed from cell to cell 



all down the pedicel (or hair) of the gland, and caused the 



sap to pass from the cells on the upper side of the pedicel 



to the lower side, and this causes the curvature of the pedicel. 



I shall work away next summer when Drosera opens again, 



for I am much interested in subject. After the glandular 



hairs have curved, the oddest changes take place viz., a 



segregation of the homogeneous pink fluid and necessary 



slow movements in the thicker matter. By Jove, I sometimes 



think Drosera is a disguised animal! You know that I always 



so like telling you what I do, that you must forgive me 



scribbling on my beloved Drosera. Farewell. I am so very 



glad that you are going to reform your ways ; I am sure that 



you would have injured your health seriously. There is poor 



Dana has done actually nothing cannot even write a letter- 



for a year, and it is hoped that in another year he may quite 



recover. 



After this homily, good night, my dear friend. Good 

 heavens, I ought not to scold you, but thank you, for writing 

 so long and interesting a letter. 



1 The doubt here expressed as to whether the result is due to actual 

 weight is interesting in connection with Pfeffer's remarkable discovery 

 that a smooth object in contact with the gland produces no effect if the 

 plant is protected from all vibration ; on an ordinary table the slight 

 shaking which reaches the plant is sufficient to make the body resting 

 on the gland tremble, and thus produce a series of varying pressures 

 under these circumstances the gland is irritated, and the tentacle moves. 

 See Pfeffer, Untersuchungen aus d. bot. Institut zu Tubingen^ Vol. I., 

 1885, p. 483 ; also Insectivorous Plants, Ed. II., p. 22. 



