742 KBPORT— 1887. 



cotyledons for ten days in the water-culture absorbed from them sufficient com- 

 bined nitrogen for their nutrition during the whole period, and to account for the 

 combined nitrogen present in the liquid after the close of the experiment. This 

 objection does not seem to be a strong one, but the point cannot be regarded as 

 finally settled until exact quantitative determinations of the nitrogen in the seed, 

 in the plant, and in the water have been made. This I hope to do in another 

 series of experiments. 



On removing the plants from the solutions at the close of the experiment I was 

 struck by certain difierences in the roots of those grown in solutions 1. and II. The 

 roots of the plants grown in solution I. were short and thick, and were entirely 

 destitute of those tubercles which so commonly occur on the roots of Le(/uminos(e ; 

 whereas those of the plants grown in solution II. were long and slender, and bore 

 a great number of tubercles. The tubercles were present on the roots both in and 

 out of the liquid. 



As I only examined the tubercles when the plants were drying up I am unable 

 to say anything as to their mode of origin or as to their normal structure. I may 

 mention one point — that in many cases the contents of the tubercle had been ex- 

 truded, leaving a delicate sac, traversed by vascular tissue, attached to the root. 



The concurrence of abundant tubercles on the roots of Leguminosse with a 

 deficiency of combined nitrogen in the soil has already been dwelt upon by De Vries 

 and others ; but the constancy of this correlation has been denied. My own obser- 

 vations lead me to support I)e Vries' view. I cannot but regard these tubercles as 

 of great importance in the nutrition of the plant. They are not mere depositories 

 of proteid substances, as is lU'ged by Tschirch and others, for they are far too small 

 to be of any significance in this direction. Moreover the structure of the cells, 

 when active, is not that of depositories. They are full of granular protoplasm, 

 including the peculiar ' bacterioid ' bodies which have been detected in them ; but 

 there does not appear to be any masses of dead proteid resembling the aleurone- 

 grains of seeds. Judging from tlie published figures of sections of active tubercles 

 the ' bacterioid ' tissue suggests the actively metabolic tissue of a gland. The ques- 

 tion is, What is the nature of their metabolic activity ? Do they assimilate free 

 nitrogen, or do they simply assimilate combined nitrogen formed in the soil (or 

 solution) by bacteria ? I am inclined to conclude that the former is the case, but 

 my observations do not warrant a definite decision on this point. I hope to arrive 

 at it by further experiment. 



5. On the Movement of the Leaf of Mimosa Pudica. 

 By S. H. Vines, B.Sc, F.B.8. 



[Preliminary communication.] 



The special object in view was to obtain some further information as to the 

 nature of the mechanism of the movements of the leaf. With this object experi- 

 ments were made to ascertain the nature of the effects produced with atropin and 

 physostigmin — alkaloids which are known to produce well-marked effects in the 

 animal body. 



Branches of Mimosa were cut off under water and were transferred to watery 

 solutions of the alkaloids. The salts used were tartrate of atropin and citrate of 

 physostigmin ; the solutions were made faintly acid with citric acid. 



Various strengths of solution were tried, but the most gradual, and therefore 

 most instructive, results were obtained with solutions of 0-25 per cent. The quan- 

 tity of solution used was 10 cc, but in no case was more than 2 or .'5 cc. absorbed 

 during the experiment, which extended over 24 to 30 hours. 



■Effect of af.rojnn : — 



a. On the main pulvimis. — The movement of the petiole on stimulation be- 



comes gradually less and less, until movement ceases altogether, the 

 petiole retaining the more or less nearly horizontal diurnal position. 



b. On the lenjlefs. — The induced movement of the leaflets is at first well 



marked, and they readily recover the expanded position ; but gradually 



