172 EVOLUTION AND GENETICS 



case does not stand alone but is duplicated by simi- 

 lar evidence from other characters subject to en- 

 vironmental changes in these flies, namely, bar eyes, 

 abnormal abdomen, and extra legs, all of which are 

 greatly affected by the environment, but the effects 

 are not transmitted. Is it surprising, then, in the 

 light of these detailed and controlled data that we 

 should look askance at claims which pretend to 

 demonstrate the inheritance of acquired characters 

 from observations that are in most cases inadequate 

 to prove the point at issue ? 



The experiments that Kammerer has carried on 

 for several years relate, for the most part, to the 

 kind of characters which I have just mentioned. He 

 finds that salamanders spotted with black and yel- 

 low change to more black or more yellow individuals 

 if kept on a black or a yellow background. Their off- 

 sj^ring reared on a neutral background show, he be- 

 lieves, some influence of the effects produced on their 

 parents, and so on. Until these results are repeated 

 on material that is more thoroughly controlled, or 

 on material where the effect produced can be stated 

 in measurable terms and not by pictures of selected 

 material, it is in my opinion better to suspend judg- 

 ment in respect to their interj^retation. The careful 

 work of Herbst that was undertaken to check up 

 Kammerer's evidence has so far found no justifica- 

 tion for Kammerer's conclusion. ^luch of the otlier 

 work that Kammerer has brought forward as evi- 



