240 Studies in Tndian Cotton 



experiments in which the 1-gland stage will be grouped with the 1 — 3 

 stage to form one intermediate group. 



Excluding types 1 — 3 and 11, in all the remaining types two forms 

 have been isolated which are characterised respectively by the absence 

 of leaf glands and by the presence of these glands in the 3 — 1 stage, 

 and both these forms have been pure bred. In type 1 the three forms 

 have all been observed but their purity or the reverse has not been 

 tested by experiment ; type 2 has already been dealt with ; in type 3 

 the 3 — 1 gland form has alone been met with, while of type 11, though 

 the 3 — 1 form has similarly been the sole one observed, it is impos- 

 sible to speak with much certainty since the plants on which the 

 observations have been made are all derived from a single source. 



In the cross between type 3 and type 4 to which reference has 

 already been made an eglandular form of type 4 was used as parent. 

 This cross, therefore, illustrates the behaviour of this gland character 

 under the influence of cross-fertilisation and the results are set out in 

 Tables XXVII and XXVIII. In the F^ generation the plants are 

 uniformly of the intermediate form (glands 1 — 3) while in the F^ 

 generation the two parental forms reappear. It will be observed from 

 Table XXVII that while the ratio between the eglandular and glandular 

 forms agrees closely with the expectation there occurs among the 

 glandular forms a large excess of that with the glands 3 — 1 and the 

 same is found to hold among the F, offspring of the impure F„ parents 

 (Table XXVIII, last two columns). 



That this excess is due to the classification of certain intermediate 

 forms as pure 3 — 1 forms is proved by the fact that 52 individuals 

 which had been so characterised were found to be in reality impure. 

 The F^ plants must in fact be considered as forming continuous series 

 from the pure eglandular form to the pure glandular 3 — 1 form though, 

 from the very nature of thecase, the former is more readily identified 

 than the latter. It has been seen that plants with a single leaf gland 

 occur; and, if the 1 — 3 stage be considered as the full intermediate, 

 this stage must be considered as an approach to the eglandular con- 

 dition. In the same manner there appears to occur a stage which 

 approaches the fully glandular condition sufficiently closely to be with 

 difficulty separated from it. By examining the plants at the end of the 

 season it is possible to distinguish two conditions which may be termed 

 the 3 — (1) stage, in which even the latest leaves of the monopodia bear 

 three glands, and the 3 — 1 stage, in which these bear only one or at 

 most two glands. It is not yet certain, however, that this distinction 



