H. Martin Leake and B. Ram Pershad 5 



This band may be narrow and sharply defined, broad and diffuse. 

 Associated with P in the impure condition, it develops a form (PTF) 

 having a pale purple margin and white eye (PL I, fig. 2). In certain 

 families the PW form approximates so closely to the crimson RP form 

 that correct determination on appearance is hardly possible. 



M, a factor which develops a mauve-purple in the margin and a 

 deeper eye (PI. I, fig. 4). As in the previous cases, this, again, may be 

 divided into two forms, a standard form, and one showing a distinct 

 crimson form by transmitted light. This factor shows complete domi- 

 nance, and the purity or reverse of any particular plant for this factor 

 is, consequently, only determinable by further culture. 



L. The nature of this factor forms the subject of discussion later; 

 for the present it may be considered an intensifier of the factor M, con- 

 verting the mauve-purple into a rich magenta-purple (PI. I, fig. 5) with 

 an associated form in which a crimson shade is apparent by transmitted 

 light. The degree of intensification is, however, very variable and, in 

 practice, the entire purple group forms a continuous series in which, 

 while it is possible to distinguish with certainty plants which carry the 

 factor L, it is not possible to distinguish those lacking this factor with 

 the same degree of certainty. It is impossible, thus, to separate a 

 mixed culture into two groups according as they do, or do not, possess 

 that factor. 



The five groups which arise from the combination of these factors 

 are as follows : 



I. The white-eyed group. In this group the P and R factors occur, 

 but the M factor is absent. The following forms are recognisable : 



Pppr VL or LP very light, or light pink 



PPpp P full pink 



PpRR i ^^ purple white eye 



PPRp ) 



PPRR [ ^^ red-purple white eye 



II. The purple group. In this the M factor, or the M and L 

 factors, occur, but from it the P factor is absent. 



The various forms are all purple. When the L factor is absent the 

 colour is invariably a light mauve-purple, MP, but when it is present, 

 a series, varying from the true mauve-purple to a full magenta-purple, 

 PL, is obtained. 



III. The dilute colour group. In this group the marginal colour is 

 dilute and the eye coloured. Both the P and the M factors are present, 



