or-; 



TORREYA 



LIBRARY 

 NEW YORK 

 OOTANICAL 



CiARDBN. 



June, 1909 

 Vol. 9 No. 6 



EXPERIMENTS UPON DROSERA ROTUNDIFOLIA 

 AS TO ITS PROTEIN-DIGESTING POWER 



By Winifred J. Robinson 



A repetition, with some extensions, of a part of Darwin's ex- 

 haustive series of experiments on the digestive power of the 

 leaves of Drosera rotundifolia was undertaken with the purpose 

 of ascertaining whether the purer proteins now available would 

 give any different results from those obtained by Darwin with 

 tissue fragments or crude protein materials, solid and liquid. 

 The experiments were carried on at the New York Botanical 

 Garden under the direction of Professor William J. Gies, of the 

 College of Physicians and Surgeons of Columbia University. 



The plants used were collected in the bogs near Lakewood, 

 N. J., in July, 1907. They were planted in sphagnum at the 

 propagating house of the New York Botanical Garden, where 

 they were kept continuously except when certain of their num- 

 ber were brought to the laboratory of the garden for a short time 

 for observation. 



The proteins used were prepared at the College of Physicians 

 and Surgeons under the direction of Professor Gies with the ex- 

 ception of the nucleoprotein, which was extracted from com- 

 pressed yeast by Professor Gies's method, in the laboratory of 

 the New York Botanical Garden. 



To insure accuracy in the records of the experiments a dia- 

 gram of the arrangement of the leaves of the plant was made 

 in each case, the point on a leaf where a protein particle was 

 placed being indicated on the diagram by an ink spot. Observa- 

 tions of the plants brought to the laboratory were made at 

 ^ intervals of from ten to thirty minutes during the first half day, 



" ^ [No. 5, Vol. 9, of ToRREYA, comprising pages 8g-io8 was issued April 30, I909.] 



^ 109 



