CHAP. I. CYTISUS. 37 



rise did not coincide with that of the great diurnal fall, so that 

 narrow ellipses were described, as is the usual rule with circum- 

 nutating organs. The cotyledons are provided with a pulvinus, 

 and its development will hereafter be described. 



Mimosa pudica (Leguminosse). The cotyledons rise up verti- 

 cally at night, so as to close together. Two seedlings were 

 observed in the greenhouse (temp. 16 to 17 C. or 63 to 65 F.). 

 Their hypocotyls were secured to sticks, and glass filaments 

 bearing little triangles of paper were affixed to the cotyledons of 

 both. Their movements were traced on a vertical glass during 

 24 h. on November 13th. The pot had stood for some time in 

 the same position, and they were chiefly illuminated through 

 the glass-roof. The cotyledons of one of these seedlings moved 

 downward in the morning till 11.30 A.M., and then rose, moving 

 rapidly in the evening until they stood vertically, so that in this 

 case there was simply a single great daily fall and rise. The 

 other seedling behaved rather differently, for it fell in the morn- 

 ing until 11.30 A.M., and then rose, but after 12.10 P.M. again fell ; 

 and the great evening rise did not begin until 1.22 P.M. On the 

 following morning this cotyledon had fallen greatly from its 

 vertical position by 8.15 A.M. Two other seedlings (one seven 

 and the other eight days old) had been previously observed 

 under unfavourable circumstances, for they had been brought 

 into a room and placed before a north-east window, where the 

 temperature was between only 56 and 57 F. They had, more- 

 over, to be protected from lateral light, and perhaps were not 

 sufficiently illuminated. Under these circumstances the coty- 

 ledons moved simply downwards from 7 A.M. till 2 P.M., after 

 which hour and during a large part of the night they con- 

 tinued to rise. Between 7 and 8 A.M. on the following morning 

 they fell again ; but on this second and likewise on the third 

 day the movements became irregular, and between 3 and 10.30 

 P.M. they circumnutated to a small extent about the same spot ; 

 but they did not rise at night. Nevertheless, on the following 

 night they rose as usual. 



Cytisus fragrans (Leguminosae). Only a few observations were 

 made on this plant. The hypocotyl circumnutated to a con- 

 siderable extent, but in a simple manner namely, for two hours 

 in one direction, and then much more slowly back again in 

 a zigzag course, almost parallel to the first line, and beyond the 

 starting-point. It moved in the same direction all night, but 

 next morning began to return. The cotyledons continually 



