428 ENTOMOLOGICAL NEWS. [Dec. , '07 



is extraordinarily favorable. The precisely determinable char- 

 acter of differences in color, in pattern, in venation details, in 

 numbers of spurs, spines and hooks, in linear dimensions, etc., 

 coupled with the ease of collecting long - series of individuals 

 bred in identical or determinably different conditions of cli- 

 mate, locality, season, altitude, etc., make insects very available 

 material for studies in variability. Such intensive studies as 

 those of Miss Enteman on Polistes and Tower on Leptinotarsa 

 well illustrate the possibilities and the value of insects to stu- 

 dents of variation. 



In experimental studies in heredity the availability of insects 

 as Versuchs-object is marked. The rapidity and the prolific- 

 ness of reproduction enable a student to get data from hosts of 

 individuals in a single year. Miss McCracken gets six and 

 seven generations of Lina and Gastroidea each season in her 

 elaborate investigation of the behavior of inheritance in these 

 dichromatic and sporting species. She breeds and examines 

 carefully and obtains 'quantitative data from 50,000 pedigreed 

 individuals a year as a basis for generalizations. Compare this 

 with the laboriously and expensively derived data from the 

 birds and fnammals so commonly used in experimental studies 

 in heredity. Using silkworms, representing a dozen races, most 

 of them well distinguished and stable, I have been able to get 

 inheritance data representing from ten to thirty thousand indi- 

 viduals a year. 



In the field of distribution and isolation studies, much may 

 be done now and much more as our faunistic knowledge of 

 insects increases. But intensive studies, like Shelford's with 

 the tiger-beetles, show how pertinent are the data to be derived 

 from such studies. 



It is, of course, familiar knowledge that the development of 

 the various theories connected with the relation of color and 

 pattern to surroundings, viz., the theories of protective and 

 aggressive resemblance, of warning colors, of directive colora- 

 tion, of alluring and recognition marks, and of mimicry, has 

 been almost wholly based on studies of insects. Bates, Belt, 

 Muller, Poulton and Marshall have built up their interesting 

 theories almost wholly from conditions found in the insect 



