JLLoyp] ABSCISSION OF FLOWER BUDS 61 
are based, together with those of Balls! in Egypt, indicate that the 
water deficit is the cause of rise of temperature in the tissues, and that 
this constitutes the stimulus which directly leads to abscission. 
If the general conclusion that the grand march of shedding is due 
to the depletion of moisture in the deeper soil be true, irrigation and 
better soil manipulation are indicated as remedies. It has been shown 
experimentally by Barre? in South Carolina, that irrigation has the 
effect of inhibiting shedding. The observations of Balls that the rise 
of the water-table in Egypt due to the Nile floods, by asphyxiating 
the deeper roots and so limiting the water-supply, causes severe 
shedding, are quite in harmony with the above findings, since too 
much water may have quite the same effect as too little, and suitable 
drainage is thereby indicated as surely as irrigation. It remains to 
suggest also that the use of fertilizers on the soil which tend to in- 
creasing its water-holding capacity may also contribute to a desirable 
result.® 
The belief has been expressed that high temperatures are also 
responsible for shedding. It is however very questionable that the 
highest air-temperatures recorded during the four seasons in question, 
(90 to 100 degrees Fahr.) have been directly responsible, but rather 
that, with high temperatures there may occur, if other conditions 
contribute their effect, higher transpiration rates, and marked daily 
wilting with closure of the stomata, inevitably procuring high inter- 
nal temperatures which may be effective. 
The data upon which the above results rest will appear in full 
elsewhere. 

1 Balls, W. Lawrence, The Cotton Plant in Egypt, pp. 202, London, 1912, and 
several other contributions. 
? Unpublished results kindly communicated to me by letter. 
3 Mr. R. G. Arnold has written me that during a period between July 25 and 
Aug. 5, during which shedding was marked in adjoining ground, the shedding in 
an experimental plot was entirely checked by the application of 200 pounds of sodium 
nitrate. 
4Lloyd, F. E. Leaf Water and Stomatal Movement in Gossypium, and a 
Method of Direct Visual Observation of Stomata. Bull. Torr. Bot. Club. 40: 
1-26, Jan. 1913. 

Sec. IV, Sig. 2 
