216 Studies in Indian Cotton 



The results detailed in Table II may now be expanded to include 

 greater detail and the group possessing sap colour divided according 

 to the intensity of that colour. This expansion is effected in Table V. 

 Correcting the totals in this table as far as subsequent experiment 

 renders possible the numbers become, DD 373, DR 810, RR 384, 

 giving a ratio of I'OO : 2-17 : 1-03. The widest variation from the 

 expected result occurs in the cross between type 2 and type 3. This 

 is a cross between two monopodial types, and, for reasons already 

 explained, it has been found almost impossible to handle this cross, 

 which has not, in consequence, been carried beyond the F2 generation. 

 It is impossible, therefore, to say how far the lack of the pure dominant 

 form is real. It is noticeable that this lack is associated with a large 

 proportion of the impure vein form and that, consequently, the deter- 

 mination from the leaf may not be as accurate as in the cases more 

 fully investigated. 



In the above considerations on the behaviour of the red colouring 

 matter in the sap no distinction has been drawn between the various 

 types used in which this colouring matter is absent. It is necessary 

 briefly to consider these types under two groups, namely those in which 

 the petals are yellow and those in which the petals are white. It is 

 the identical cross made by Major Trevor Clarke and, as described by 

 Watt (20) (page 336), one on which he founded great hopes. These 

 experiments of Trevor Clarke are the subject of frequent note in the 

 Journal of the Agri-Horticultural Society of India of that date (1867- 

 1870), but no full details have been traceable. A similar cross is referred 

 to by Fletcher (22). Here again full details are not given but, in as far 

 as both red arid yellow flowered plants appeared in the Fi generation, 

 it would appear that the red parent plant was a heterozygous form. 



(i) Type 3 x type 4. Type 3 possesses a full red colour both in the 

 foliage and flower which in type 4 is absent, the foliage of this type 

 being consequently green and the petals yellow. The cross, which has 

 been carried as far as the Fs generation, may be taken as an example of 

 the case in which the first of these groups is employed. The results 

 obtained from this cross are set out in Table VI. The numbers 

 obtained in this series bear a ratio in close accordance with Mendelian 

 expectation and it is evident that in this cross an example of the 

 simplest case occurs, namely that in which a single pair of allelomorphic 

 characters is concerned. This pair is composed of the two factors — 

 presence or absence of the red colouring matter — the present condition 

 possessing partial dominance over the absent. This being so, it follows 



