228 Studies in Indian Cotton 



intermediate groups are given in a condensed form so that the offspring 

 of all plants, the average leaf factor of whose offspring differs by O'lO or 

 less, are grouped together. Full details of individual plants are only 

 given at the two points where the change from the pure to the impure 

 form takes place. It will be seen from this table that a marked 

 difference exists in the behaviour of the individuals belonging to the 

 three groups into which the F^ parents fell. The offspring of those 

 Fn individuals of which the leaf factor was less than 2 have, with few 

 individual exceptions, a leaf factor which is less than 2. In the same 

 manner the offspring of plants with the leaf factor greater than 3'2 

 have a leaf factor which is greater than 3. As will be seen from the 

 table the exceptions are relatively few and it may be said in general 

 terms that the individuals of the two groups, having the leaf factor less 

 than 2 and greater than 32 respectively, are pure with regard to this 

 character. The dotted vertical lines in the Table drawn between the 

 columns representing the values 2"1 and 2*2, and between those repre- 

 senting the values 2*8 and 2*9, indicate the limits of experimental error 

 recognised in the two groups. It will be noticed that in 5 only out 

 of 1283 cases the limiting value of 2*1 is exceeded and in 7 out of 

 1274 cases the limiting value of 2*9 is not reached. These exceptions 

 will form the subject of further investigation. It is, of course, possible 

 that these plants have been introduced by accident. Nothing, however, 

 in the further examination of these individuals lends support to this 

 view. 



The third group, which is characterised by the intermediate value 

 of the leaf factor, is not, like the previous groups, pure in this respect. 

 Such plants have invariably given offspring which, as a group, exhibit 

 the entire range of values obtained for the leaf factor. It will be noted 

 that, though this variability exists, the average value of the leaf factor 

 of the Fs generation from this intermediate group differs but slightly 

 from the mean of the two parental values and further that the number 

 of individuals comprising the three groups are in almost complete 

 accordance with Mendelian expectation (1 : 2*04 : 1), while the mean 

 values of leaf factors for the three groups taken severally show but 

 slight variation from the values obtained for the corresponding groups 

 of the jPa generation. 



It is impossible to avoid being impressed by the similarity which 

 exists between these results and the more typical examples of 

 Mendelian phenomena. 



It has frequently been pointed out {vide Bateson (3), p. 53) that 



