Principles of Heredity 123 



Here again a vast number of varieties can be at once 

 classified into round and wrinkled (the classification 

 commonly used), others are intermediate normally. Here 

 also I suspect some fairly clear sub-divisions might be 

 made in the wrinkled group and in the round group too, 

 but I would not assert this as a fact. 



I cannot ascertain from botanists what is the nature of 

 the difference between round and wrinkled peas, though no 

 doubt it will be easily discovered. In maize the round 

 seeds contain much unconverted starch, while in the 

 wrinkled or sugar-maize this seems to be converted in 

 great measure as the seed ripens ; with the result that, 

 on drying, the walls collapse. In such seeds we may 

 perhaps suppose that the process of conversion, which in 

 round seeds takes place on germination, is begun earlier, 

 and perhaps the variation essentially consists in the pre- 

 mature appearance of the converting ferment. It would be 

 most rash to suggest that such a process may be operating 

 in the pea, for the phenomenon may have many causes ; 

 but however that may be, there is evidently a difference of 

 such a nature that when the water dries out of the seed on 

 ripening, its walls collapse* ; and this collapse may occur 

 in varying degrees. 



* Wrinkling must of course be distinguished further from the 

 squaring due to the peas pressing against each other in the pod. 



In connexion with these considerations I may mention that 

 Vilmorin makes the interesting statement that most peas retain their 

 vitality three years, dying as a rule rapidly after that time is passed, 

 though occasionally seeds seven or eight years old are alive ; but 

 that wrinkled peas germinate as a rule less well than round, and 

 do not retain their vitality so long as the round. Vilmorin-Andrieux, 

 Planless Potageres, 1883, p. 423. Similar statements regarding the 

 behaviour of wrinkled peas in India are made by Firminger, Gardening 

 for India, 3rd ed. 1874, p. 146. 



