II DEVELOPMENT AND ENVIRONMENT 17 



ll/faximum, Blaok-bulb in uacuo 



■<-i II- 



Critical Period Sub-soil Water Period Autumnal Period 



Height of Stem 



TTT K: I I 13 1 II t I I ^ I I I I I I 



-|T-T M I I I I I I 1^ 



July 



Aug. 



Sept. 

 20 28 1 



11 19 27 4 12 



Envikonment. Gbziea, Cairo. 1911. 



on intermediate dates take intermediate times, vary- 

 ing, of course, with the particular weather which they 

 experience. 



The proportion of seeds which successfully complete 

 their " field-germination " also varies — other tilings being 

 equal — ^with the sowing-date. The lowest proportions are 

 found in the very early and very late sowings, though for 

 totally dissimilar reasons. The failures in the first 

 instance are almost entirely due to a damping-off" fungus, 

 known as " Sore-shin," which we must consider in further 

 detail, not merely because it is the only serious fungoid 

 disease of cotton in Egypt, but rather because certain 

 conclusions drawn from the study of its relations to 

 temperature will be used extensively for interpreting the 

 growth-processes of its host. 



The « Sore-shin " fungus.' ^ "— This facultative 

 parasite was first described in 1895 by Mr. G. F. Atkinson 



c 



