[LLOYD] ABSCISSION OF FLOWER BUDS 57 
obscure. There appears also to occur an inhibition period during 
flowering so that abscission is usually consummated either before or 
after, but not during anthesis. There was no evidence from which it 
could be certainly concluded that the period for small and large squares 
were different in length. When the operations were performed in 
the evening, the responses followed more rapidly in both bolls and 
squares by about 12 hours. The cause of this appears to lie in the 
night period of high turgidity following the operation. 
Large bolls occupy more time in abscission than small ones 
because of the greater amount of tissue to be affected and because 
of its character. Complete shedding in a literal sense is not possible 
in some instances in which the abscission tissues run obliquely down 
the stem. This becomes more manifest with increasing age, serving 
to illustrate the possible resistance to abscission offered by older tissues. 
When older bolls can be shed at all, the period required is scarcely 
more than two to four days longer than that for small bolls. 
The stimuli applied by wounding are however probably much 
more intense and are followed by shorter response periods than those 
which usually obtain in the field, excepting severe insect injury and 
those following, say, a very hot wind, such as the simoon in Egypt. 
Since there is no doubt of the relation between intensity of stimulus 
and rapidity of response, it became necessary to imitate field conditions, 
as far as might be possible, in order to determine the time limits of 
periods for responses of minimum rapidity. From branches kept 
in a humid atmosphere the bolls and squares were shed over a period 
of eight days with a maximum on the third or fourth, squares being 
somewhat less ready to respond than bolls. Root-pruning experiments 
though less conclusive under the conditions under which they were done 
showed that the response period lay within four days. The destruc- 
tion of the pollen by water shortly after pollination was followed by 
a high percentage of shedding covering a period extending from the 
fourth to the ninth day inclusive, with the maximum frequency on 
the sixth day. The same cause, but imposed by rain, had the same 
result with high frequencies on the sixth and eighth days. Slight in- 
jury, sufficient merely for the removal of parts to prevent fertilization 
and reducing the possible wound-shock to a minimum, produced 
results quite in accord with the above, the consequent shedding 
occurring from the third to the tenth days inclusive, with the maximum 
frequency for all operations on the sixth. A greater amount of injury, 
but not so severe as in those referred to in a previous paragraph and 
done in such a manner as to imitate the initial injury inflicted by 
insect larvæ, caused shedding on the third to the eighth days thereafter, 
with the maximum on the fifth. 
