PLANT HYBRIDIZATION BEFORE MENDEL 253 



of the 817, the colors of all four of the grandparents were also 

 known. 



"The upshot is," he says, "that I have had the good fortune to discuss 

 a total of 817 hounds of known colour, all descended from parents of 

 known colour. In 567 out of the 817, the colours of all four of the grand- 

 parents are also known; in 188 of the latter, in turn, the colours of all 

 eight great-grandparents were also known." (p. 404.) 



Gal ton's remarks with reference to his effort to find a lule that 

 would apply with respect to what might be presumed to be sex- 

 linked inheritance, or as it was then called sex-prepotency, are 

 interesting as showing the manner in which it was possible to 

 arrive at conclusions upon this point by means of the statistical 

 method. 



"Our first inquiry then must be, 'is or is not one sex so markedly pre- 

 potent over the other in transmitting colour, that a disregard of sex 

 would introduce statistical error*?' In answering this, we should bear in 

 mind a common experience, that statistical questions relating to sex are 

 very difficult to deal with." Large and unknown disturbing causes ap- 

 pear often to exist, that make data that are commonly homogeneous very 

 heterogeneous in reality. "Some of these are undoubtedly present here, 

 especially such as may be due to individual prepotencies combined with 

 close interbreeding. . . ." 



The results were derived from two classes of data ; one, derived 

 from individuals of which all the grandparents were known, 

 amounting to 567 individuals ; the other, of which all the grand- 

 parents were not known, amounting to 250 individuals. These 

 data, as Galton states, 



". • . will be seen to disagree widely, concurring only in showing that 

 the dam is prepotent over the sire in transmitting colour." 



Taking the data from the two respective classes separately, the 

 former, called the "A" data, gave relative prepotency as 58:51, 

 or 114: 100. The second set, or the "B" data, gave a relative ratio 

 of prepotency as 47 : 32 or 147 : 100. Taken together, the data give 

 a combined ratio of 54:45 or of 120:100, i.e., as 6 is to 5. (pp. 

 404-5.) 



It was found that a certain amount of preferential activity 

 took place, exhibited by the tendency to use tricolors as sires, 

 so that reciprocal matings were not equally numerous. "Still," 

 Galton remarks, "on the application of a general test, the error 

 feared is too insignificant to be observed." (p. 405.) 



