Mason. — Growth and Abscission in Sea Island Cotton. 461 
bolls being shed when from five to nine days old. A large proportion of 
the more mature bolls, when shed, were affected with external boll disease 
(P seudomonas Mctlv ace arum). It has, of course, long been recognized that 
both bacterial and fungous diseases of the boll and insect punctures, or any 
other factor liable to cause injury, increase the susceptibility to shedding. 
An indication of the part played by the physical environment in 
initiating abscission, and the more pronounced tendency of the flower-buds 
and bolls produced during the later part of the flowering period to undergo 
Fig. 4. Rates of boll-shedding, flower production, evaporation, and rainfall. Gp. II. 
abscission, can be obtained from the graphs in Figs. 3 and 4. The daily 
rates of flower production and boll-shedding are exhibited for both groups, 
but of bud-shedding only for the first group. For comparison with these 
shedding rates, the evaporation from the Livingston ( 5 ) spherical black 
atmometer and the rainfall have also been inserted. The daily rates of 
flower production have been smoothed to four-day means, and the shedding 
rates, evaporation, and rainfall to two-day periods. Attention should be 
drawn to the small proportion of bolls shed during the earlier portion of the 
flowering period. The results indicate that quite a small stimulus during 
the later part of the flowering period may result in a relatively large 
