352 



MODIFIED CmCUMNUTATION. 



Chap. VII 



TrifoHum resupinatum : circumnutation 

 and nyctitropic movements of the ter- 

 minal leaflet during 24 hours. 



curved, broken line. The terminal leaflet, therefore, of this 

 species described during the daytime only a single additional 



ellipse, instead of two ad- 

 ditional ones, as in the 

 case of T. suhterraneum. 

 But we should remember 

 that it was shown in the 

 fourth chapter that the 

 stem circmnnutates, as no 

 doubt does the main petiole 

 and the sub-petioles; so 

 that the movement repre- 

 sented in fig. 143 is a com- 

 pounded one. We tried 

 to observe the movements 

 of a leaf kept during the 

 day in darkness, but it 

 began to go to sleep after 

 2 h. 15 m., and this was 

 well pronoTinced after 4 h. 

 30 m. 

 Trifdlium repms. — A stem was secured close to the base of 

 a moderately old leaf, and the movement of the terminal leaflet 

 was observed during two days. This case is interesting solely 

 from the simplicity of the movements, in contrast with those of 

 the two preceding species. On the first day the leaflet fell 

 between 8 a.m. and 3 p.m., and on the second between 7 a.m. 

 and 1 P.M. On both days the descending course was somewhat 

 zigzag, and this evidently represents the circumnutating move- 

 ment of the two previous species during the middle of the day. 

 After 1 P.M., Oct. 1st (Fig. 144), the leaflet began to rise, but 

 the movement was slow on both days, both before and after 

 this hour, until 4 p.m. The rapid evening and nocturnal rise 

 then commenced. Thus in this species the course during 24 h. 

 consists of a single great ellipse; in T. resupinatum of two 

 ellipses, one of which includes the nocturnal movement and is 

 much elongated; and ia T. suhterraneum of three ellipses, of 

 which the nocturnal one is likewise of great length. 



Securigera coronilla (Tribe 4). — The leaflets, which stand 

 opposite one another and are numerous, rise up at night, come 

 into close contact, and bend backwards at a moderate angle 

 towards the base of the petiole. 



