58 THE ROYAL SOCIETY OF CANADA 
The frequencies of the shedding responses following boll-weevil 
injuries are determined by the intensity of stimulus, oviposition 
causing relatively little, and the feeding of the larva the most shedding. 
From these experiments taken all together, it may be concluded 
that stimuli supplied under field conditions usually make themselves 
evident as total responses within ten days, with the maximum fre- 
quency not later than the sixth day, especially during the earlier 
portion of the season. This conclusion receives support from the dif- 
ference in size of shed bolls and persistent bolls, the difference being a 
measure of the length of the time the total response has occupied, 
assuming that growth is inhibited as a part of the general abscission 
response. This period proves to be four to six days. When larger 
bolls are involved, as may occur under severe conditions which are 
more likely to prevail at the end of the season, the abscission period 
is increased. It was found, in 1907, that after flowering had ceased, 
the periods required to account for the shedding rates observed was 
in the neighbourhood of eight, or, as a probable maximum, ten days. 
Conclusions from observation of shed bolls. The conclusions thus 
arrived at receive further support from the detailed history of particular 
flowers. The data, which were derived from the individual records 
of 579 flowers during the season of 1912, show that the ages at 
which bolls are shed under field conditions were from two to 25 days. 
The highest frequencies were for bolls of four to eight days, the data 
for two sets of plants, taken separately (lots 2 and 5, 1912), indicating 
that under more stringent conditions as to water supply the highest 
frequency may be for bolls four days old, under less stringent cir- 
cumstances six days. 
By experiments it was shown that bolls may be shed when one 
and two days old in relatively high frequencies, in response to stimuli 
applied before anthesis, provided the stimuli applied are severe enough. 
The shedding of open flowers, meaning the intervention of the response 
between the beginning and end of anthesis (regarding the first 24 
hours after the first opening of the flower as the period of anthesis), 
appears not to take place. There appears therefore to occur an in- 
hibition of abscission for this period. When open flowers are recorded 
as shed, it has always been evident that abscission was complete at 
the beginning of anthesis. 
It seems therefore highly probable, amounting almost to a cer- 
tainty that, when bolls are shed in the field, the stimulus accountable 
for their shedding occurs at or subsequent to anthesis in the great 
majority of cases. The abscission period for any bolls found to be 
shed will therefore be equal to or less than its age. When shed as 
the result of inadequate fertilization the age and abscission period are 
