RESEARCH SEMINAR. 31 I 



by Pearson, were proven for Cynthia of this year (1898-1899). 

 Annual series of the same species exhibited the same phenomena. 

 Three lots of Cccropia have been likewise examined, in much 

 greater detail (28 characters), and these also show both kinds of 

 selection. 



An enquiry into the occurrence of reproductive selection grew 

 naturally out of the foregoing. Two annual series of Cynthia 

 (more than two hundred matings) and two annual series of Cc- 

 cropia (130 and 125 matings respectively) have afforded the basis 

 for the following conclusions : Pupal characters of mating males, 

 or females, when compared with similar characters of the non- 

 mating males, or females, prove to be different in type and re- 

 stricted in variability. Thus a third period of selection is shown 

 to be correlated with variability. 



In discussing the nature of the selective processes, reasons 

 were given for regarding the correlations between the several 

 characters as the real bases for the action of eliminating processes, 

 and not the individual characters themselves. 



Further studies, now in progress, were briefly described. 

 These deal with the phenomena of correlation between characters 

 of the individual in its successive larval, pupal and imaginal con- 

 ditions ; with inheritance in pure breeds, and in mixed breeds ; 

 and with the correlation of certain physiological reactions with 

 structural characters. 



July 2j. White Feathers. By R. M. STRONG. 



The few references in the literature of feather coloration to the 

 causes of white in feathers state that the whiteness is due to the 

 presence of air in the feather substance. This is misleading, for 

 the larger proportion of the white effect is produced by the bar- 

 bules which do not have air-spaces of significant size. The bar- 

 bules are white for the same reason that powdered ice or glass 

 and other transparent substances in a fine state of division appears 

 white. 



July 2+. Nervous Regulation of the Heart of Venus Merce- 



naria. By R. A. BUDINGTON. 



The details of the nervous control of the heart of vertebrates have 

 been w r orked out in more and more minuteness since the time when 



