122 BOTANY AND INTENSIVE CULTIVATION 



For the germ cells the units which join together 

 in pairs to produce the individual, are units in 

 the sense that they lack the dual nature of the 

 individual. They are single-barrelled guns and 

 hence are charged or uncharged. The individual 

 which carries the full double charge gives rise to 

 germ cells all alike with respect to this character. 

 They are all charged. But the individual which 

 carries one charge only gives rise to two kinds of 

 germ cells ; half have the charge and half lack it. 

 Hence when the germ cells of two such similar 

 individuals unite in pairs the result can be predicted. 

 On the average in four unions one will be between 

 germ cells charged with the power of developing 

 the character, two between cells one of which is 

 charged and the other not, and one between un- 

 charged germ cells. The first combination will 

 produce an individual pure to the character. 

 Mated with a similar individual he will produce 

 offspring all of which possess the character in 

 question. The second combination will produce 

 an individual which may show the character as 

 markedly as the first; but posterity will betray 

 his hybrid nature : for mated with a similar indi- 

 vidual his offspring will be not uniform but 

 divisible into the haves and have-nots as in the 

 case just described. The third combination, of 

 uncharged germ cells, will result in an individual 

 lacking the character, and on the evident principle 

 of ex nihilo nihil fit such an individual pure bred 



