Ill 



On the Supposed Antagonism of Mendelian 

 to Biometric Theories of Heredity 



(Manchester Memoirs, Vol. xiix., 1905, No. 6) 



Dissensions in scientific matters may be said to be of two 

 kinds, of which one is a disagreement about fact and can 

 be settled by an appeal to fact, while the other is the con- 

 flict of theoretical interpretations which cannot be so easily 

 concluded. When Owen said that an ape's brain had not 

 a hippocampus minor and Huxley asserted that it had, 

 Flower announced that he had an ape's brain in his pocket ; 

 and the dissection of the brain put an end to the discussion. 

 But in the second form of controversy no such touchstone 

 can be applied, and in the debate on heredity at Cambridge 

 this year Mendelian maize-cobs were displayed in vain. Of 

 this kind of controversy there are again two sorts, one in 

 which the theories put forward by the opposite factions 

 are mutually exclusive, and another in which, while there 

 is apparent incompatibility, the truth of both of the hypo- 

 theses is ultimately demonstrable. It remains to be seen 

 to which of these subdivisions the Cambridge debate,^ and 

 the wider discussion of which it was the outcome, are to 

 be assigned. If the two theories are mutually exclusive, 

 which is right ? If, on the other hand, they are not, how 



^ Tliis essay is so arranged that if the reader is not interested in the 

 phenomenon of hybridisation he may leave out Part 2. 

 2 Reported in Nature, Vol. 70, pp. 53S-9. 



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