A New TJieory of Heredity. . 97 



It may seem to some that the assumption that the egg 

 contains particles capable of producing an uiispecialized 

 epithelial cell which shall have the power to give rise to 

 all the specialized sorts of epithelial cells, involves just as 

 much comjilexity of structure as the assumption that 

 each kind of cell is represented m the ovum, but I think 

 an illustration will show that this is not the case. 



T]"aining of a certain kind will develop a boy into a 

 good pedestrian, while another sort of training will make 

 him a good shoemaker; but it is surely simpler to assume 

 that he is born with a power to develop the charac- 

 teristics of a shoemaker under the influence of certain 

 conditions, and those of a pedestrian under other condi- 

 tions, than to assume that he is born with all the pecu- 

 liarities of both latent in his organization. 



The direct modifying influence of surrounding condi- 

 tions is a subject upon which very much remains to be 

 done, but we know enough about it already to state that 

 many of the constant characteristics of organisms are due 

 to exposure to constant and uniform conditions rather 

 than to heredity. To what extent this is true we are 

 quite unable to determine, but we can be sure that the 

 organization of the ovum is simpler, and in all prob- 

 ability vastly simpler, than that of the developed or- 

 ganism. 



After all these deductions are made the number of 

 strictly hereditary features is very great indeed, and the 

 egg of one of the higher animals must be a marvellous 

 structure, for we know that, after all, most of the charac- 

 teristics of an oriranism are not due to the influence of 

 its conditions of life, but to the past history of the race; 

 and Darwin has shown us that the successive changes 

 which have resulted in the evolution of any organism 

 do not, usually, owe their existence to the direct modify- 



