HEEEDITY 



fail to reveal the occurrence of spontaneous 

 generation, that is, the origin of living beings 

 other than from pre-existing living beings. 



In asexual methods of reproduction a new 

 individual arises out of a detached portion of 

 the parent individual. Such methods of origin 

 are varied and interesting, but do not concern 

 us at present. In all the higher animals and 

 plants a new individual arises, by what we call 

 a sexual process, from the union of two minute 

 bodies called the reproductive cells. They are 

 an egg-cell furnished by the mother and a 

 sperm-cell furnished by the father. 



There is a great difference in size between 

 egg and sperm. The egg is many thousand 

 times greater in bulk, as seen in Fig. 1, for 

 example, yet the influence of each in heredity 

 appears to be equal to that of the other. This 

 fact shows unmistakably that the bulk of the 

 reproductive cell is not significant in heredity. 

 A large part of the relatively huge egg can 

 have no part in heredity. It serves merely as 

 food for the new organism, furnishing it with 

 building material until such a time as it can 

 begin to secure food for itself. The essential 



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