1914] The OfTAWA Naturalist. 47 



as it is acceptedly called, as shown bv figures derived from a 

 study of Egyptian cotton by Balls (15)' and of the Alabama up- 

 land plant by myself. Balls found that upwards of 90 per cent, 

 of the bolls shed did so within three of four davs after flowering. 

 From a statistical examination*^ of 579 shed "bolls at Auburn, 

 Ala., it emerged that the distribution of shed bolls, according to 

 age, shows that the vast majority of bolls are shed at the ages 

 of from three to seven days inclusive, and have at shedding a 

 diameter of 12 mm. or less. In fact, 95 per cent, are shed before 

 the end of ten days. (Figure 2). 



.*^ 



o^ 



^o^^'- 







-13 



A OF AM) SIZE OF BOLLS 

 AT SHEDDING. 



16 25 



Figure 2. Graphs for age and size of bolls at shedding in percentage 

 of the total shed. {Gossypium herhaceum) . 



The so-called "shelling" of grapes, which mav greatly 

 reduce the crop just at the period of maturation, appears to be 

 the result of a definite abscission process comparable to the 

 shedding of the cotton boll, except that the plane of separation 

 occurs at the base of the ripened ovarvand not at the base of 

 the pedicel. 



There are instances of indehiscent fruits in which excep- 

 tional behaviours may be seen, of which that of Polygonum 

 vtrginianum and of the wild rice (Zizania spp.), maybe quoted. 



« Based upon data collected by my then assistant, Mr. C. S. Ridcrway, 

 who has kindly referred them to me. 



