130 THK i{6le of nitrogen in plant-metabolism, iv., 



A. — Experiments with Vic la sativa. 



The pods of the Wild Tare, Vicia sativa, growing in the 

 open fields, were collected in March, and in widely different 

 stages of their development. 



Stage 1. — Very immature seeds, small, soft and green; 100 

 of these seeds in the fresh, moist state, with skins, weighed 

 0-9 gm. 



Stage 2. — Older seeds, larger, soft and green; 100 of these 

 weighed 31 gms. 



Stage 3. — Very ripe seeds, dry, hard and black; 100 of 

 these seeds weighed 1-7 gms. 



Method of experiment. — The material collected was imme- 

 diately brought into the laboratory, and the seeds separated 

 from the pods. The weight of one hundred moist seeds was 

 found ; and amounts of the entire seeds, with skins left on 

 and in their original fresh moist condition, were weighed out 

 for the experiment, within ten minutes of their separation 

 from the plants in the field. About 0-5 gm. was taken for 

 the estimation of the total nitrogen, by Kjeldahl's method; 

 the seeds were dropped into a flask, with HoSO^, and heated, 

 with addition of potassium bisulphate, and with copper sul- 

 phate as an accelerator. The heating was continued for six 

 hours, and the ammonia distilled in the usual way. 



A weighed quantity was next crushed in a moi'tar, and 

 quickly transferred to a flask, with about 500 cc. of distilled 

 water; heated on a water-bath at 80° C, for two hours; and 

 the fluid decanted through muslin. After adding another 

 half litre of water to the flask, the extraction was continued 

 for one hour; after which, the fluid was poured off, and the 

 operation repeated twice, in all four extractions. The residue 

 of insoluble material in the flask, was then pressed in the 

 fllter-cloth, and discarded. The combined fluids were then 

 measured, and filtered clear through filter-paper, and a 

 definite amount evaporated, on the water-bath, to a small 

 volume; this was poured into alcohol, making the liquid uj) 



