66 PATHFINDERS OF PHYSIOLOGY 



ber of chromosomes, which regularly occurs in the division of all of its 

 cells, and in all forms arising by sexual reproduction, the number 

 is even/' 



Whatever the offspring is, it is potential in the fertilized ovum. 

 If this is the contribution of each parent, the role performed by the 

 mother is that of custodian of her embryonic charge until birth. Her 

 power- to alter it in any way is as futile as that of the father. The 

 parent is rather the trustee of the germ plasm than. .the- producer of 

 the child. Sir Michael Foster once said, "The animal body is in reality 

 a vehicle for the ova; and after the life of the parent has become 

 potentially renewed in the offspring, the body remains as a cast-off 

 envelope whose future is but to die." The germ plasm is "the lighted 

 torch handed on from one runner to another." Et quasi cursores 

 vitai lampada tradunt. This equally true of plant life, where the 

 plant matures and dies leaving the future offspring potentially in the 

 seed. How characteristics are transmitted from ancestor to offspring 

 is not known. 



NOTE: — It has been estimated that the number of cells entering into the 

 composition of the body of an adult human being is about twenty-six million 

 five hundred thousand millions (26,500,000,000,000). 



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