AN EXUBERANT TERMINOLOGY 109 



A discussion of the different modes of hereditary resemblance 

 is somewhat hampered by an exuberant terminology, and by 

 the fact that different authors have sometimes used the same 

 term in different ways. We read of inheritance being unilateral 

 and bilateral, unisexual and bisexual, blended and conspired, 

 neutralised and combined, direct and collateral, atavistic and 

 progressive, and so on. We have tried to reduce this complex 

 terminology to a minimum. This is the more justifiable since 

 we cannot doubt that all the ordinary phenomena are of a piece, 

 that many of the ordinary modes will be embraced eventually 

 in one general formula — probably some modification of Galton's 

 Law of Ancestral Inheritance, and that others will be embraced 

 in Mendelian formulae. 



We propose, then, to restrict attention to three frequently 

 occurring modes of hereditary resemblance, which are called 

 blended, exclusive, and particulate. 



§ 2. Certain Necessary Saving Clauses 



Before we define and illustrate the three commonest modes of 

 inheritance, we must, at the risk of reiteration, notice certain 

 saving clauses. 



We have seen that cases of apparently very complete hereditary 

 resemblance may be illusions due to our inability to appreciate 

 the differences that really exist ; but on the other hand, we must 

 guard against the error of supposing that the frequently con- 

 spicuous differences between offspring and their parents neces- 

 sarily means an incompleteness in the inheritance itself. The 

 fact that the resemblance often reappears in the third generation 

 shows that the incompleteness is often not in the inheritance, 

 but simply in its expression. The characters were probably 

 there in posse in the germinal matter, but they were neutralised, 

 kept latent, silenced — we can only use metaphors — by other 

 characters, or else they never met with the stimulus necessary 



