EXPERIMENT WITH A PLANT 159 



sometimes used among seedsmen in so wide a sense 

 as to signify peas with a maple seed- coat. The 

 strain which I have used were given me by Mr. 

 R. H. Lock. In the case of all the pairs of characters 

 excepting that relating to the distribution of flowers 

 on the stem, the two varieties named differ from one 

 another only in respect of the two characters which 

 they are stated in the Table to bear. 



The simplest way of obtaining a result to illustrate 

 the ratio obtained when two pairs of characters are 

 involved {see Plate III.) is to cross a yellow wrinkled 

 variety with a green round one. A good yellow 

 wrinkled one to use is British Queen, and a good 

 green round Express, 



The best way of exhibiting the results of crosses 

 involving characters either of the seed-coat or of 

 the cotyledon is to mount them in cotton wool in 

 glass-topped cardboard boxes about three-quarters 

 of an inch deep. Figs. 11, 12, 21, 26, and 27, and 

 Plates I. and III. are direct photographs from speci- 

 mens mounted in this way. The method is as 

 follows : Plenty of cotton wool is laid in the box ; 

 half of each of the pods is cut off at the base, and 

 the peas attached to it are gummed into the other 

 half. The specimen is now laid on the cotton wool 

 and the lid put in its place and kept there with 

 seccotine. The whole process requires patient and 

 careful manipulation. 



