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THE AMERICAN NATURALIST [Vol. XLVHI 



therefore, if, when disturbed, they retire into still deeper 

 crevices. But I am unable to discover the adaptiveness 

 of the response of the larvae of Anthothrips niger to light 

 —at first negative, on being disturbed, but soon becoming 

 positive. Nor can I understand why the males of Ana- 

 phothrips striatus are more definitely negative to light 

 than are the females or larva?. These reactions seem to 

 me to be useless. 



"We need not demand that all of these responses be 

 adaptive, any more than that they be purposeful. Ee- 

 sponses have arisen, no one knows how. They have been 

 preserved, and we can but speculate as to the method of 

 their preservation. Natural selection may be respon- 

 sible for the preservation of the useful, and it may have 

 eliminated responses that were harmful. But other re- 

 sponses of no value whatever, but likewise harmless, may 

 have been allowed to persist, without help or hindrance 

 from selection. 



(To be continued.) 



