438 



THE MAINTENANCE OF SPECIES 



Independence of the Germplasm 



The germplasm, or the sexual cells that carry the load of hereditary 

 possibilities, and the somatoplasm, which makes up the body of the 

 individual, although to a certain extent dependent upon each other 



in a nutritional way, are 

 remarkably independent. 

 Despite the popular idea to 

 the contrary, it is extremely 

 improbable that changes 

 wrought by, or impressed 

 upon, the somatoplasm ex- 

 ercise any modifying influ- 

 ence upon the accompanying 

 germplasm. The somato- 

 plasm is simply like a casket 

 in which the jewel of germ- 

 plasm reposes. No decora- 

 tion or elaboration of the 

 casket will have any material 

 effect upon the jewel within. 

 This point has been con- 

 vincingly brought out, along 

 with other cumulative evi- 

 dences, in a critical experi- 

 ment performed in 1911 by 

 Castle and PhiUips. These 

 investigators successfully 

 transplanted the ovaries of 

 a black guinea pig into a white guinea pig whose own ovaries had 

 been removed. Later, after recovery from the operation, when 

 this white female with the borrowed ovaries of the black female was 

 mated with a white male guinea pig, the offspring were all black, 

 although both their parents were white, and under ordinary circum- 

 stances would produce only white offspring. This shows that 

 temporary residence within a white somatoplasm did not in any way 

 affect the character of the black-producing germplasm that had been 

 grafted into the white body. 



The establishment of the fact of the practical ineffectiveness of 

 somatic influence upon the germplasm has far-reaching applications 



Diagram of ovarian transplantation experi- 

 ment by Castle and Phillips, to show the lack 

 of somatic influence on the f^erniplasm. The 

 ovaries of a black guinea pig were engrafted 

 into a female albino whose ovaries had been 

 removed. Upon recovery this female was 

 mated three times with an albino male. All 

 the progeny were black. (From Walter, 

 Genetics, by permission of The Macmillan 

 Company, publishers.) 



