INHERITANCE 231 



rnents in hybridisation, which indeed seems to be the most 

 important of all for the theory of inheritance, if taken 

 together with the fact of the pureness of the germs. The 

 rule of Mendel always relates to one single character of 

 the species or varieties concerned in hybridisation, and if 

 it deals with more than one character, it regards every one 

 of them separately ; indeed, the rule holds for every one 

 of them irrespective of the others. We cannot study here 

 how this most important fact of the independence of the 

 single characters of a species with regard to inheritance 

 leads to the production of new races, by an abnormal 

 mixture of those characters. We only take advantage of 

 the fact theoretically, and in doing so, I believe, we can 

 hardly escape the conclusion that the independence of 

 the single characters in inheritance, taken together with 

 the pureness of the germ-cells in the most simple form 

 of hybrids, proves that there occurs in inheritance a sort 

 of handing over of single and separate morphogenetic 

 agents which relate to the single morphogenetic characters 

 of the adult. We may use Bateson's word " allelomorphs ' 

 for these agents, or units, as they may be called, thereby 

 giving expression to the fact that the single and separate 

 units, which are handed over in inheritance, correspond to 

 each other in nearly related species without being the same. 



And so we have at least an inkling of what the material 

 continuity of inheritance is to mean, though, of course, our 

 " single and separate morphogenetic agents," or " units " or 

 " allelomorphs ' are in themselves not much more than 

 unknown somethings described by a word ; but even then 

 they are " somethings." 



Besides the researches relating to the rule of Mendel 



