MacDougal: Some Cokkklations of Leaves 505 



growing near by were also available for comparison. The earlier 

 part of the season was one of extreme drought. During the 

 period of fifty-two days between April i6, a week before the be- 

 ginning of the test, a total precipitation of (mly i cm. was recorded. 

 It was noted that the scales and stipules were of longer duration 

 and presented the appearance of increased superficial extension 

 upon the delaminated branches within a fortnight after beginning 

 the tests. The development of leaves and buds appeared to have 

 almost ceased and an anatomical examination was made June 3-10 

 with the following results : 



The greatest length made by branches which had been defoliated 

 from the beginning was 18 cm., while a length of 25 and 30 cm. 

 was found in normal branches; 18-20 leaves had been formed 

 on defoliated branches and but 14 or 15 on normal ones. The 

 basal internodes of the twigs showed but little difference in length 

 in the two instances, being as much as 2 cm., although less in some 

 cases. The internodes formed later in the season on the normal 

 twigs attained a length of as much as 3.5 cm. in some instances, 

 while those of the defoliated twigs varied from 1.5 cm. to one 

 third that length. Consequently the defoliated twigs were closely 

 crowded at the terminal part with scales and stipules. This 

 crowding effect was accentuated by the fact that one or two small 

 leaves were thrust out of the axillary buds, although no general 

 activity of the bud was exhibited. In contrast with the behavior 

 o{ Acer, it could not be made out that any extra number of lateral 

 buds on the elder parts of the branches below had been induced 

 to awaken. 



The correlative alterations in the stipules were very marked 

 and consisted in changes in form, size, position, structure and 

 period of endurance. Normal stipules of the cherry are thin- 

 membranaceous, and generally of a reddish tinge containing almost 

 no chlorophyl. These stipules are usually short-lived and fall off 

 in such manner that on the above date they could be found onh- 

 on two or three leaves on the terminal portions of twigs. The 

 stipules on twigs on which the leaves had been dissected were 

 both broader and longer, offering a superficial expansion of about 

 five times the normal (see /. /). The maximum measurements 

 were but little greater than those of normal stipules formed earlier 



