344 INTRODUCTION TO EVOLUTION 



Guyer that antibodies (pp. 109-110) might function in this way. Perhaps 

 antibodies, if produced by changes in the body, would react with the germ 

 cells in such a way as to change the latter. 



In their experiments Guyer and Smith (1918-1924) concentrated atten- 

 tion on the crystalline lens of the eye. In earlier experiments a solution of 

 lens substance (obtained from rabbits) was inoculated into fowls. The 

 fowls formed antibodies against the foreign substance (p. 109). The fowl 

 serum containing these antibodies was inoculated into pregnant rabbits. 

 Some of the offspring of the latter were born with degenerate or mal- 

 formed eyes. It looked as though the anti-lens antibodies had interfered 

 with eye formation in the developing embryos. Had an inheritable change 

 been produced in these embryos? When the young were raised and bred 

 it was found that the eye defects were indeed inherited by subsequent gen- 

 erations. The nature of inheritance approximated that characteristic of re- 

 cessive genes. Of particular significance was the fact that males passed the 

 defect on to their offspring. If only females had done so the "inheritance" 

 might have resulted from direct transference of antibodies from the blood 

 of a mother to the blood of her offspring, since the two bloods are in 

 close contact during all embryonic development. But no such close con- 

 tact exists between a father and his developing offspring; his sole contribu- 

 tion to the latter is a sperm cell, consisting almost wholly of chromosome 

 material. Hence anything a father passes on to his offspring must be con- 

 tained in his germ plasm. 



Was this, then, a case of inheritance of acquired characters, the ac- 

 quired character being eye defect? Inheritance of acquired characters in 

 the Lamarckian sense would involve a change in the body which would 

 then be transferred to the germ plasm. In the present instance it is possi- 

 ble that the outside agent, the antibodies, acted on the eyes of the embryos 

 and on the genes of those embryos directly. If so this would not constitute 

 inheritance of acquired characters in the strict sense. 



Guyer and Smith performed one experiment which came closer to meet- 

 ing specifications for a demonstration of inheritance of acquired charac- 

 ters. They took advantage of the fact that the crystalline lens is not in 

 contact with the blood stream, and that an individual will form antibodies 

 against the lens material of his own eye if his blood is artificially brought 

 into contact with that lens material. This contact was made when the lens 

 of the eye of an anesthetized male rabbit was broken up by means of a 

 needle; surrounding blood vessels then penetrated the damaged area. The 

 male was subsequently mated to a normal female. Seven young were born 

 to this pair of parents; four of the young had defective eyes. Unfortunately 



