Tricotyls as Half Races and Intermediate Races. 351 



we rarely get more than low percentages; but it is obvious 

 that we should not expect all the seed-parents in the held 

 to furnish the same number of tricotylous seedlings. Com- 

 mercial seed is almost certain to be a mixture and to 

 }'ield a mean proportion, which may perhaps be much 

 lower than the seed of those specimens would yield. 

 which were the richest in tricotylous offspring. It fol- 

 lows from this that we can only form a proper estimate 

 if we select a group of plants among our first sowing 

 and harvest their seeds separately, if possible after tak- 

 ing the precaution of preventing too much cross-fertili- 

 zation by Insects. It is obvious that in such a culture a 

 choice will have to be made, and as a rule the tricotyls, 

 using this term in its widest sense, will be selected. From 

 the separate harvest of these selected specimens, individ- 

 ual hereditary coefficients may then be obtained. 



In spite of every precaution, the choice of the plants 

 will depend mainly on chance, for, as we shall see later, 

 tricotyls are by no means more likely to reproduce the 

 anomaly than some of the dicotyls. On the contrary, 

 plants much better in this respect sometimes occur among 

 these: but we have at present no other means of dis- 

 covering them except by growing their seed. Experience 

 however has shown that if we allow a fairly large group 

 to ripen their seed we may become independent of chance 

 in so far that we can be fairly sure that at least some 

 seedparents will give a relatively high proportion, pro- 

 vided of course that the original mixture contains such 

 amongst its components. It will soon be seen that in 

 spite of all apparent intermediate degrees, two main 

 groups can be distinguished. In one of them we find 

 only low individual values, from to 3%, or very little 

 over; in the second, on the other liand. besides these 



