74 



SCIENCE. 



[N.S. Vol. XIX. No. 471. 



be recorded the carotid pulse, the respiration, 

 the time in seconds and the rate of muscular 

 movements. Experiments made with this ap- 

 paratus show that the curve of carbon dioxide 

 excretion during work closely resembles that 

 of the pulse, and that carbon dioxide is at 

 least in part the cause of the secondary rise 

 in the pulse rate observed by Bowen. 



Dr. W. B. Pillsbury detailed some experi- 

 ments on ' The Attention Wave as a Measure 

 of Fatigue.' Not merely the daily rhythm of 

 fatigue and practise of the typical morning 

 and evening workers was reilected in the ratios 

 of the period of visibility to the period of 

 invisibility in the attention wave, but the de- 

 gree of fatigue on days of severe work as 

 compared with easy days had a corresponding 

 variation in the fluctuation of attention. In 

 the morning, practise shows itself in a con- 

 tinuous increase in efficiency through at least 

 a considerable portion of the experiment; 

 while in the evening there is a decreasing 

 effectiveness almost from the beginning. As 

 further substantiation of the theory that the 

 attention wave is closely related to the Traube- 

 Hering or Mayer vaso-motor waves, it was 

 noted that both have the same daily rhythm 

 of length. Frederick 0. Newcombe, 



Secretary, 



DISCUSSION AND CORRESPONDENCE. 



MORGAN ON EVOLUTION AND ADAPTATION. 



To THE Editor of Science: I have always 

 supposed that what are generally called La- 

 marckian views of evolution were considered 

 with less prejudice by biologists in the United 

 States than in England or Europe, and that my 

 own publications in support of such views were, 

 therefore, likely to be known and read in 

 America even if they were almost completely 

 ignored by my own countrymen. 



I find, however, that Dr. Thomas Hunt Mor- 

 gan in his book ' Evolution and Adaptation,' 

 which has just appeared, makes no mention 

 whatever of my book ' Sexual Dimorphism in 

 the Animal Kingdom, a Theory of the Origin 

 of Secondary Sexual Characters,' which was 

 published in London more than three years 

 ago. Any biologist, American or other, has 

 a perfect right to reject all my conclusions, 



but it seems to me that an author who de- 

 votes a great part of his book to the discussion 

 of Darwin's theory of sexual selection and the 

 evolution of secondary sexual characters, in en- 

 tire ignorance of the facts and arguments which 

 it cost me years of labor to collect and elabor- 

 ate, lays himself open to the charge of writing 

 without proper knowledge of the literature of 

 his subject. I have published the results of ex- 

 perimental work apart from this, but the only 

 reference Dr. Morgan makes to it is to a 

 popular article in Natural Science; he has 

 not apparently consulted the original memoirs. 



Like other English writers it has been my 

 ambition that my work should be known to the 

 scientific public of the United States, which 

 is not only very intelligent but free from prej- 

 udices which are stronger than reason in Eng- 

 land. I am much disappointed to find that 

 my chief contribution to the investigation of 

 evolution is so little known to American evo- 

 lutionists. J. T. Cunningham. 



Zoological SociETy, 



3 Hanover Square, London, W. 



mutation and selection. 



In reading Professor Morgan's very inter- 

 esting and valuable book, ' Evolution and 

 Adaptation,' it is surprising to find that he 

 apparently regards the theory of evolution 

 by selection and DeVries's mutation theory as 

 being to a degree in conflict. 



The evolution which observation shows us 

 has taken place is chiefly characterized by the 

 fact that it has brought organisms into favor- 

 able relation with their environmental condi- 

 tions. That this could have been secured by 

 mutation unaided by selection seems alto- 

 gether unlikely. 



In the case of the leaf butterflies of the 

 genus Kallima the theory of evolution by 

 mutation alone must assume that the remark- 

 able resemblance arose all at once by a single 

 mutation, or that there were a series of muta- 

 tions which for some unaccountable reason 

 were of such a character as to make the re- 

 semblance to a leaf gradually grow more per- 

 fect, though no selective action of the en- 

 vironment controlled this improvement in 

 pattern. 



