174 BREEDING 



production of a dwarf, the dwarf character is no more 

 tainted with tallness than a white counter becomes 

 pink by lying in a heap with red ones. 



The cause of the pure breeding of the 25 per 

 cent, tails appearing in the second hybrid genera- 

 tion, namely, the union of two germ cells containing 

 similar character-factors, is also well demonstrated 

 by means of these counters. So, also, is the fact 

 that the remaining 50 per cent, of the tails are 

 hybrids, and, moreover, that these hybrids of the 

 second hybrid generation will produce a third hybrid 

 generation exactly similar to that produced by the 

 hybrids of the first hybrid generation, for the reason 

 that the contents of the germ cells of both these 

 hybrids (of the second and first hybrid generation) 

 are identical. 



It is furthermore plain why, according to Mendel's 

 theory, this segregation of characters in these pro- 

 portions should continue as long as the seeds of 

 hybrid plants are sown. A hybrid, whether it occurs 

 in the first or the fiftieth hybrid generation, will pro- 

 duce germ cells half of which contain the dominant, 

 and the remaining half the recessive character ; and 

 the generations produced by them will, consequently, 

 have the same composition. But we must guard 

 against the error of assuming that Mendel's theory is 

 true, and of then dogmatically stating, from the 

 standpoint of this assumed basis, that the segregation 

 in these ratios will be continued for all time. If 

 the theory is true they will. Let us, then, turn the 

 tables ; and test its truth by finding out if they do. 



