3V8 Mr Philip Se well's Ohservations upon the 



old ; those of S. canariensis were seventy-five days old ; both 

 were placed in identically similar conditions. 



S. interrupta. — Jan. 21 : — 



Jan. 22, 10 a.m. : — 



A. 1st and 2nd leaves apart, 26 mm. 

 B 21 



C 22 



Jan. 22 and 23, at 6.30 (after exposure in open air):- 



(22nd) (23rd) 



A. 1st and 2nd leaves apart, 29 mm. 22 mm. 



cotyledons, 38 „ 38 



B. 1st and 2nd leaves apart, 23 „ 23 



cotyledons, 32 „ 32 



C. 1st and 2nd leaves apart, 30 „ 25 



cotyledons, 26 „ 26 



Further comparison in both species shows that if they are 

 placed out in open air they assume positions in which the 

 leaves are further and further apart — due to growth in 

 relation to light ; but, whenever the above species, and also 

 various others are brought into the drier air, and the greater 

 darkness of the room, they exhibit movements such as we 

 have indicated. Thus, the tips of leaves in S. canariensis 

 moved from a position, 40 mm. apart, to a position of close 

 contact, one leaf extending a little beyond the summit of 

 the other, however. 



It is perhaps not worth while to record these movements 

 at greater length. Some leaves, especially when very young 

 or old, being either too much appressed or too much 

 recurved, exhibited no movement ; thus,, within two days, 

 leaves of Tenorii moved from 57 mm. apart to 30, and back 

 to 34, whilst younger leaves retained the more fixed position, 

 11 or 12 mm. apart. Some seedlings also exhibited greater 

 divergence than others. 



Although we have considered that this movement is 

 brought about in many instances by altered conditions of 



