186 Life <in<f LcttirH of Fnincin (lalton 



for diseases ski])pin^ a {feneration. This selecting out of germs will not 

 occur in animals of pure breeds for their stirp contains only one or a very 

 few varieties of each species of germ, so that the selection will contain all, 

 and tlius the offspring resemble their parents and one another. 



"The more mongrel the breed, the g^reater is the variety of the offspring." (p. 336.) 



To this principle, however, Galton adds a limitation, the stirp cannot be 

 indefinitely increased in complexity, because there is a limit to the space it 

 occupies. There is a finite, it great, number of varieties of germs, and of the 

 individual germs in each variety. 



"TI1U8 in the gnwlual broeding out of negro blood, we may find the colour of a mulatto to 

 l)e the half, and that of a quadroon to be the quarter of tliat of his black ancestors; but as we 

 pn>ceed further, the subdivision becomes very irregular; it does not continue indefinitely in 

 the geometrie«l series of one-eighth, one-sixteenth, and sj) on, but is usually present very obvi- 

 ously or not at all, until it entirely disappears." (p. 335.) 



Turning now to the germ which has developed into a somatic cell, CJalton 

 questions whether it does produce gemmules at all— at any rate its fertility 

 is far less than that of the latent germ. Influences acting on the somatic cells 

 of the parent are only slightly or not at all represented in the like somatic 

 cells of the olfspring. He considers at some length instances of inherited 

 mutilations ana of acquired characters, and thinks they may be reasonably 

 looked upon as a 'collection of coincidences.' Even if there are real cjises 

 of changes in the somatic cells of the i)arents influencing the somatic char- 

 acters of the offspring, Galton would out admit that occjusionally gemmules 

 are thrown off by somatic cells, which find their way into the circulation and 

 ultimately obtain a lodgment in the already constituted sexual elements. 

 Such a process is, however, independent of and stibordinate to the causes 

 which mainly govern heredity (pp. 347-88). Even to the last Galton did 

 not wholly give up Pangenasis, for Darwin had accepted Brown-Sdquard's 

 epileptic gumea-pigs, yet as Galton remarked : 



"It is indeed hard to find evidence of the power of the personal structure to react upon the 

 sexual elements that is not open to serious objection." (p. 'Mb.) 



Finally I may cite: 



"Tlie hyiKithesis of organic units enables us to .specify with much i-lenrness the curiously 

 circuitous relation which connects the ofTspring with its p»ironts. The idea of its being one of 

 direct descent, in the common acceptation of tbat vague phrase, is wholly untenable, mid is the 

 chief cause why most persons seem jx-rplexed at the app<>arance of capriciousness in hereditary 

 transmission. The stirp of the child may Ix; considered t/o have <le«cende<l directly from a part 

 of the stirpsof each of its parents, but then the personal structure of the cliihl is no more than 

 an inij)erfect representation of his own stirp, and tlie jH-immal structure of each of the parents 

 is no more than an imperfect representation of each of their own stirps." (p. 310'.) 



Such a modern ideji as that parents are only conduit-pipes for the germ- 

 plasm of their stocks is fully expressed by Galton with better limitation, 

 and with fuller suggestiveness, both in this paper and in that on Blood- 



' From the modem biometric standpoint the association is 'correlational' not causal. 



