An Introduction to a Biology 



Chemistry furnishes a parallel. The chemist cannot pre- 

 dict the rate at which any given atom in a litre of oxygen 

 is travelling ; he can only deai with " statistics of average 

 conduct " ; but he can predict the result of passing an 

 electric spark in a vessel containing oxygen and hydrogen. 

 Yet he who deals with the properties of the elements may be 

 said to deal with units, and he who deals with the component 

 atoms and one can only deal with them in large numbers 

 may be said to deal with masses. 



It is true that the biometrician possesses the only means 

 of measuring the " intensity of heredity " in a non-predicable 

 case, but it seems to me that to extend the application of 

 these means to predicable cases is fallacious. If , the true 

 function of the biometrician is to give us statistics of average 

 conduct where we cannot predict individual conduct, it seems 

 to me that to deal by the biometric method with cases where 

 we can is not only unprofitable, but likely to lead men to 

 think that where there are two methods dealing with the 

 same material, of which the one can predict while the other 

 cannot, the latter is fallacious. Whereas if the biometrician 

 confined himself to the non-predicable and the Mendelian 

 to the predicable, the general conclusion would be that each 

 had his proper sphere which indeed, in my belief, he has. 

 I do not set forth these views in any spirit of dogmatic 

 certainty ; and nothing could please me less than that they 

 should go unchallenged by anyone who believes me to be 

 mistaken. 



LITERATURE REFERRED TO IN THE TEXT 



'08. DAVY, HUMPHRY. " On some New Phenomena of che- 

 mical Changes produced by Electricity, particularly 

 the Decomposition of the Fixed Alkalies, and the 

 Exhibition of the New Substances which constitute 

 their Bases ; and on the general Nature of alkaline 

 Bodies." Phil. Trans,, Vol. 98, p. 1. 



'89. GALTON, FRANCIS. " Natural Inheritance." Macmillan 

 and Co. 



'95. COUTAGNE, G. " Recherches sur le Polymorphisme des 

 Mollusques de France." Lyon. 



'97. GALTON, FRANCIS. " The Average Contribution of each 



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