HEREDITY BATESON. 361 



between the cytological characters of somatic tissues in the same 

 individual we can scarcely expect to perceive such distinctions be- 

 tween the chromosomes of the various types. 



For these methods of attack we now substitute another, less am- 

 bitious, perhaps, because less comprehensive, but not less direct. 

 If we can not see how a fowl by its egg and its sperm gives rise to 

 a chicken or how a sweet pea from its ovule and its pollen grain 

 produces another sweet pea, we at least can watch the system by 

 which the differences between the various kinds of fowls or between 

 the various kinds of sweet peas are distributed among the offspring. 

 By thus breaking the main problem up into its parts we give our- 

 selves fresh chances. This analytical study we call Mendelian be- 

 cause Mendel was the first to apply it. To be sure, he did not ap- 

 proach the problem by any such line of reasoning as I have sketched. 

 His object was to determine the genetic definiteness of species; but 

 though in his writings he makes no mention of inheritance it is clear 

 that he had the extension in view. By cross breeding he combined 

 the characters of varieties in mongrel individuals and set himself 

 to see how these characters would be distributed among the indi- 

 viduals of subsequent generations. Until he began this analysis 

 nothing but the vaguest answers to such a question had been attempted. 

 The existence of any orderly system of descent was never even sus- 

 pected. In their manifold complexity human characteristics seemed 

 to follow no obvious sj^stem, and the fact was taken as a fair sample 

 of the working of heredity. 



Misconception was especially brought in by describing descent in 

 terms of " blood." The common speech uses expressions such as 

 consanguinity, pure-blooded, half-blood, and the like, which call up 

 a misleading picture to the mind. Blood is in some respects a fluid, 

 and thus it is supposed that this fluid can be both quantitatively and 

 ■qualitatively diluted with other bloods, just as treacle can be diluted 

 with water. Blood in primitive physiology being the peculiar vehicle 

 of life, at once its essence and its corporeal abode, these ideas of 

 dilution and compounding of characters in the commingling of 

 bloods inevitably suggest that the ingredients of the mixture once 

 combined are inseparable, that they can be brought together in any 

 relative amounts, and in short that in heredity we are concerned 

 mainly with a quantitative problem. Truer notions of genetic 

 physiology are given by the Hebrew expression " seed." If we speak 

 of a man as " of the blood royal " we think at once of plebeian dilu- 

 tion, and we wonder how much of the royal fluid is likely to be " in 

 his veins " ; but if w^e say he is " of the seed of Abraham" we feel 

 something of the permanence and indestructibilitj'^ of that germ 

 which can be divided and scattered among all nations, but remains 

 recognizable in type and characteristics after 4,000 years. 



