212 Studies in hidian Cotton 



under-surface of the mid-rib. A detailed discussion of the leaf glands 

 is reserved for subsequent treatment. 



The experiments. 



In the crosses that have been made between pairs of the above 

 types the characters that have been observed in greatest detail include 

 the following : 



(a) The colour of the corolla. 



(b) The red colouring matter of the sap. 



(c) The leaf factor. 



{d) The type of branching and length of vegetative period, 

 (e) The leaf glands. 



3 (a). The colour of the corolla. 



In all the types of Indian cottons now under consideration, there 

 occurs at the base of each petal a deep-red or purple spot or " eye." 

 The remainder of the petal is uniform, either yellow in colour or white, 

 while in the two types, 3 and 11, the colour is red (cf. Plate XXXV). 

 The red colouration of the petals in these two types is simply a mani- 

 festation of the red sap colour which is present throughout the plant. 

 It is not characteristic of the petals alone and cannot be dealt with 

 exclusively as such. 



According as the factor producing the yellow colour is present or 

 absent, there arises a simple pair of allelomorphic characters peculiar 

 to the corolla, of which the presence of the colour producing factor 

 is dominant. This is shown in the cross between a type with yellow 

 petals and one with white petals. 



The results of such a cross between type 4, with a yellow, and 

 type 6, with a white, flower are set out in Table I. 



In the F^ generation of this cross the plants are all yellow, the 

 colour being indistinguishable from the yellow of the parent type 4. 

 The yellow is completely dominant. 



In the F2 there occurs a separation into two groups, yellow-flowered 

 and white-flowered. The numbers handled are not large and small 

 weight can be attached to the ratio of 2'1 yellow to 1 white obtained, 

 in which the proportion of yellow is considerably below expectation. 

 It is noteworthy, however, in this connection that throughout the 

 provinces where these types are cultivated, although the crop presents 



