Correlation and Application of Statistics to Problems of Heredity 87 



Galton's interest in Discontinuous Evolution was further manifested in 

 the same year by a circular which will be found in the Transactions of the 

 Entomological Society of London, 1895 (April 3rd). It consists of three 

 questions addressed to breeders and others, not only entomologists but to 

 those who pursue any branch of natural history. The questions are for 

 information on the following topics : 



"(i) Instances of such strongly-marked peculiarities, whether in form, in colour, or in habit, 

 as have occasionally appeared in a single or in a few individuals among a brood; but no record 

 is wanted of monstrosities, or of such other characteristics as are clearly inconsistent with 

 health and vigour. 



"(ii) Instances in which any one of the above peculiarities has appeared in the broods of 

 different parents. [In replying to this question, it will be hardly worth while to record the 

 sudden appearance of either albinism or melanism, as both are well known to be of frequent 

 occurrence.] 



"(iii) Instances in which any of these peculiarly characterised individuals have transmitted 

 their peculiarities, hereditarily, to one or more generations. Especial mention should be made 

 whether the peculiarity was in any case transmitted in all its original intensity, and numerical 

 data would be particularly acceptable that showed the frequency of transmission: (a) in an 

 undiluted form, (/;) in one that was more or less diluted, and (c) of its non-transmiss-ion in any 

 perceptible degree." 



The context attached to the questions shows that Galton was still 

 troubled by the question of regression: " Regressiveness and stability are 

 contrasted conditions and neither of them can be fully understood apart 

 from the other." As I have endeavoured to indicate regression is merely a 

 statistical result, which holds for a population, not for an individual, when 

 we table the former with a knowledge of only a limited number of the 

 kinsfolk of individuals and assume the mean of each generation to remain 

 the same*. The biological problem is to determine how this mean changes 

 and is quite independent of the statistical idea of regression. As I have 

 indicated above (p. 83) the offspring of selected ancestry on Galton's own 

 theory do not regress to the population mean, and in this respect the only 

 contrast that could be drawn between the offspring of a "sport" and of such 

 selected ancestry is the question of the extent to which a sport breeds true 

 without having even a limited amount of selected ancestry. This is really 

 the point which Galton's third question would tend to answer f. 



K. Eugenics as a Religious Faith. I have already pointed out that a very 

 fundamental characteristic of Galton's mind was his desire that our pro- 

 gressive knowledge of natural law should at once be turned to practical service 

 in attempts to elevate the race of man. He could not think of the doctrine of 



* This assumption is made by Galton, but it is not in the least needful to the statistical theory 

 of regression, which measures each generation from its own mean. 



f I am not certain whether it was in reply to this circular that Galton received information 

 about a singular family of lunatic cats. He described the family in a letter to The Spectator 

 (April 11, 1896), entitled: Three Generations of Lunatic Cats. The sires of the kittens were 

 unknown, but may be assumed to have been normal. Nevertheless the lunacy, which may be 

 considered as a sport, was transmitted by the mother to all her offspring and grandchildren 

 with undiluted strength. The only doubt that can be raised is whether the sire of "Phyllis," who 

 was brought from Ewart Park, Northumberland, might possibly have been a wild cat. It is a 

 pity the family could not have been preserved for the study of hereditary lunacy. 



