298 TRANSACTIONS OF THE [Sess. lxxviii. 



or in ovules. In the pith cells of the peduncle, at the level 

 of insertion of the corolla, there was found a greater 

 accumulation of starch granules than in the normal 

 flower. 



No trace whatever of insect attack, of fungus mycelium, 

 or of any other such stimulus has been detected. 



Various experiments were performed with a view to 

 determining the influence, if any, of gravity and light on 

 the curvature of the corolla. The specimens selected for 

 experiment were both young and old, the former being 

 still straight in bud, the latter already bent. The amount 

 of curvature is measured by the angle subtended by the 

 peduncle and the middle line of the corolla tube. The 

 flowers were fixed in water, in test tubes, and experiments 

 were carried on in dark and in light. 



1. Geotropism. — Buds, when fixed vertically and kept 

 in the dark, expanded slightly, but showed no curvature, 

 even after the lapse of four days. From this it may be 

 inferred either that gravity alone is insufficient to induce 

 curvature, or that in the absence of light as a tonic 

 condition no response is made. 



From experiments with adult flowers conflicting results 

 were obtained. One whose angle of curvature was 40° 

 was fixed with the peduncle upright. The angle of 

 curvature increased by 13° in three days. This appears 

 to be an attempt on the part of the flower to reassume its 

 diatropic position. On the other hand, two flowers whose 

 angles of curvature were 90°, were fixed, peduncles hori- 

 zontal and corolla tubes vertical, one pointing upwards 

 and the other downwards. No movement from the erect 

 position was observed. Presumably the inference to be 

 drawn is, as in the first case, viz. : either that gravity has 

 no effect, or has no effect in the absence of light. 



2. Geotropism and Heliotropism. — In the following ex- 

 periments the flowers were unilaterally illuminated, and 

 the force of gravity was not eliminated. 



Of the four buds experimented upon, two being placed 

 horizontal and two vertical, only one of the former showed 

 any movement. It curved slightly upwards towards the 

 light. 



In the case of adult flowers one increased its angle of 



