knowledge op heredity in pistjm. 99 



3. — Colour of the Testa, Corolla, and Leaf Axils. 



Mendel's observations upon these characters extended only 

 to the simplest possible case. Stated in general terms, his 

 result is perfectly correct. When a plant with purple flowers 

 and pigmented axils and testas is crossed with an unpigmeuted 

 plant, the characters of the coloured plant are dominant and 

 Mendelian segregation occurs. If the colour characters are 

 studied more minutely, however, the case is found to be 

 somewhat complicated, and it will be convenient to classify 

 the main colour characters examined by the present writer in 

 the following manner. 



A. Testa. — (i.) A grayish or brownish pigmentation (gray), 

 as opposed to the absence of this pigmentation (white) — in the 

 latter case the testa is faintly greenish or yellowish or nearly 

 colourless. There are probably several subdivisions of each 

 of these two classes which could be distinguished by a 

 sufficiently skilful observer, but the writer finds it necessary 

 to be content with the statement that the two classes are 

 allelomorphic to one another. 



(ii.) The presence (purple spotted) of bright purple spots or 

 dots, very variable in extent, as opposed to the presence of a 

 few very faint bluish or reddish dots only. The two classes 

 are readily distinguishable if the seeds have ripened in dry 

 weather. But in wet weather difficulties may arise, since the 

 purple pigment is soluble in fresh water — a fact which may 

 possibly account for some of the supposed irregularities in the 

 behaviour of this character. 



(iii.) The presence of the maple character (maple) — a mar- 

 bling or mottling of a rich brown colour, as opposed to the 

 absence of this pigmentation. 



Purple spotted and maple are only clearly visible when gray 

 is also present ; but maple may be faintly recognizable on 

 white plants, constituting what I have elsewhere (15) described 

 as " ghost maple." Purple is completely masked, and maple 

 partly masked, in the absence of gra3^ 



The purple spotting is produced by a pigment dissolved in 

 the sap of certain cells immediately underljring the outermost 

 cell layer of the testa. The brown colour of the maples is 



