1^0 BREEDING 



peas when they germinate; for, inasmuch as round 

 and wrinkled peas are equally round before they lose 

 their water, and are equally round when they have 

 taken it up again, we have some ground for assuming 

 that each kind takes up as much when it germinates 

 as it loses when it ripens. The fact, therefore, that 

 a wrinkled pea takes up more water than a round 

 one does, when it germinates, may be taken to mean 

 that it loses more than a round one does when it 

 ripens. 



The theory that less of the sugar in the wrinkled 

 pea is converted into starch is supported by the 

 well-known fact that wrinkled peas are sweeter than 

 round ones, and also by the fact that all the favourite 

 eating peas on the market are wrinkled ones. 



We are now in a position to give tentative answers 

 to the questions : What is it that determines round- 

 ness ? and, What is it that determines wrinkledness ? 

 and then to indicate the way in which the presence 

 and absence hypothesis applies to this pair of 

 characters. 



In a round pea, it would seem that all the sugar 

 is converted into starch ; in a wrinkled one, only part 

 of it is ; and the wrinkling is primarily due to the 

 escape of the water from the solution of sugar left 

 over after ripening ; and, consequently, in the last 

 resort, due to the absence of that which completes 

 the conversion of the sugar into starch or, at any 

 rate, to an insufficiency in the quantity of that 

 substance, whatever it is. The round pea has the 

 full dose — to use Mr. Bateson's phrase — of this 



