ABSORPTION OF NUTRIMENT BY INSECTIVOROUS PLANTS. 



269 



Each pot was marked by a letter, and every prepared leaf had a 

 number stuck by the side of it, corresponding with which notes were 

 made. The time was observed at the beginning and end of the pre- 

 paration of each plant. 



Method of examination.'^ — The. time elapsing between the pre- 

 paration of the plants and their examination was found by successive 

 trials to be the best when between 45 and 50 hours, which was there- 

 fore adopted. At the expiration of this time they were taken, plant 

 by plant, and leaf by leaf, in the order in which they were prepared 

 and the stalks of the prepared leaves were first severed at the plant- 

 end by a fine pair of scissors; next, the blade of the leaf with the 

 remains of the fly was cut ofi", and then the stalks after being washed 

 with distilled water were dried in linen. Their length in centimetres 

 were also found, so that the distance the lithium had travelled through 

 the stalk from the leaf-end could be ascertained, and finally its plant- 

 end was introduced into a gas flame burning in front of a direct-vision 

 spectroscope, when the presence of the lithium was revealed by its 

 characteristic spectrum. 



Explanation of the Table. — For convenience the results thus ob- 

 tained have been tabulated ; on the left-hand side are the particulars 

 of the preparation of the plant, and on the right hand those of their 

 examination. The fourth column on the right-hand side contains a 

 list of various parts of the plants which were examined for lithium 

 absorbed from the flies placed on the prepared leaves of the plant. 

 The distance in mms. from the plant-end of the prepared leaf-stalks 

 to the point where the lithium was found, is given in the third 

 column. The remainder appears to require no explanation. 



Series I. — All D. rotundifolia except P and U, D. intermedia. 

 Preparation. Examination. 



Time. 

 July 15th, 



2.25 p.m. 



2.46 p.m. 



la 

 II 



2 cms. 

 2 cms. 

 2.1 cms. 

 2.3 cms. 



Hi 



0) a 2 



si-! 



6 mm.. 

 3.5 mm 

 fO mm. 

 5 mm. 







One old & 



1 young 



leaf. 



11 



P 



Young leaf. 



• There were two series of experiments commenced eariy in June on the 

 Droseras before that which is here given as Series T., in order that the best con- 

 ditions of success might be ascertained. I hope that at some future time I shall 

 be able to arrive at some accurate results as to the rate at which absorption takes 

 place. 



t mm. signifies that it had reached the extremity of the plant-end of the 

 stalk. 



X The parts of the plants here mentioned were all washed in distilled 

 water and dried in linen previous to examination. 



