

NOTES AND COMMENT 



Dr. Frank E. Lutz, writing in The American Naturalist for February, 

 has trenchantly criticised zoological experimenters for neglecting humid- 

 ity as an environic factor of importance to animals, or for doing even 

 worse in ascribing phenomena to temperature causes when humidity 

 was neither controlled nor measured. A recent treatise on experimental 

 entomology is cited in which much more space is devoted to a discussion 

 of the literature of temperature effects than to that of all other factors 

 together. Attention is called to the fact that animals suffer a water 

 loss, which must be influenced by atmospheric humidity as surely as is 

 the water loss of plants, and experiments are cited from the work of 

 Tower to show that the influence of different humidities on. the degree 

 of melanism or albinism in beetles is as great as that of temperature and 

 is similar to it when gradients of change are plotted . 



It is very gratifying to have a man become vehement in his denuncia- 

 tion of methods or tendencies of which he disapproves, for he thereby 

 testifies to the sincerity of his convictions and takes the surest mode of 

 commanding attention. Dr. Lutz is very emphatic in his views regard- 

 ing the use of empirical rather than experimental methods in seeking 

 the causes of the distributional limitation of species. He says, "The 

 study of distribution was long, and still is, largely an effort to get the 

 ranges of animals and plants to fit isotherms. When yearly averages 

 do not work, winter minima or summer maxima or accumulated tem- 

 peratures are tried." 



Dr. Lutz then cites the work of Transeau as being a successful attempt 

 to avoid the adhesion to isotherms, saying ' ' Transeau has sho\\Ti that 

 if we plot the ratio of temperature to humidity we get a very close 

 correspondence between distribution and climatic factors." Although 

 the matter is not vital to the contentions of Dr. Lutz, it is necessary to 

 state that the ratios plotted by Transeau were not those of temperature 

 to hmnidity but those of rainfall to evaporation rate. 



A recent bulletin of the Agricultural Department on American-grown 

 paprika describes an investigation into the possibility of replacing the 

 importation of this condiment by its production at home. The bulletin 



133 



