Manchester Memoirs, Vol. xlviii. (1904), No. 24. 3 



conception of that phenomenon. Galton said : " The two 

 parents contribute between them on the average one-half, 

 or (o'5) of the total heritage of the offspring ; the four 

 grand-parents, one quarter, or (0"5)' ; the eight great- 

 grandparents, one eighth, or (0'5)^, and so on. Thus the 

 sum of the ancestral contributions is expressed by the 

 series {(o-5) + (o-5)^-l-(o-5/, &c.}, which, being equal to i, 

 accounts for the whole heritage." (Galton '97 p. 402.) 



(3) Mendel's Investigations. 



Mendel, an account of whose life and a translation of 

 whose work has been given by Bateson {;.Q2.a) conducted 

 hybridization experiments with peas in the cloister garden 

 of the monastery at Briinn of which he was Abbot. He 

 had found that peas differed from one another in respect of 

 seven characters, only one of which, for the sake of sim- 

 plicity, I propose to consider ; that is, the colour of the 

 seed : this was either yellow or green. When he crossed 

 a green-seeded pea with a yellow-seeded pea, the hybrid 

 which he obtained was always the same with regard to 

 that character ; it was always a yellow-seeded pea. 

 Yellow-seededness therefore was called a dominant char- 

 acter ; and greenness of seed a recessive character. When 

 the hybrids were allowed to breed (they were self-fertilized), 

 a curious result was obtained : 25^ of the offspring were 

 green-seeded and 75^ yellow-seeded. Now it will 

 be remembered that the hybrid was yellow-seeded ; and 

 also that that was the character of one of the parents of the 

 hybrid ; so that by mere inspection of the yellow-seeded- 

 ness of this 75%, we cannot tell whether they are all 

 pure yellows, or all hybrids, or some pure yellows and 

 some hybrids. But we can tell this by breeding from 

 these yellow-seeded peas ; for it is known that pure yellows 

 breed true, and we have just seen that hybrids produce 



