Adaptation to Environment 341 



is of course an entirely different thing from stating 

 that by inducing the midwife toad to lay its eggs in 

 the water the male offspring acquires the pads and 

 horns of other species of frogs on its thumb; or that 

 by keeping black salamanders on yellow paper the off- 

 spring is more yellow. Yet if there is an inheritance of 

 acquired characters which can in any way throw light 

 on the so-called phenomena of adaptation it must 

 consist in results such as Kammerer claims to have 

 obtained. 



While the writer does not decline to accept Ehrlich*s 

 interpretation of the arsenic-fast strains of trypano- 

 somes or Kammerer's statements in regard to the inheri- 

 tance of acquired character, he feels that more work 

 should be done before they can be used for our problem. 



7. This attitude leaves us in a quandary. The 

 whole animated world is seemingly a symphony of 

 adaptation. We have mentioned already the eye 

 with its refractive media so well curved and placed 

 that a more or less perfect image of the outside objects 

 is focussed exactly on the retina; and this in spite of 

 the fact that lens and retina develop independently; 

 we have mentioned and discussed the cases of instincts 

 or automatic arrangements which are required to per- 

 petuate life — the attraction of the two sexes and the 

 automatic mechanisms by which sperm and egg are 

 brought together; the maternal instincts by which the 

 young are taken care of; and all those adaptations by 



