106 CARNEGIE INSTITUTION OF WASHINGTON. 



"Miss EUinor H. Behre has recently undertaken a continuation of much 

 of the work done by former assistants and the carrying out of some further 

 studies hitherto impossible, or possible in only a very limited way. 



"During the past year Miss Mary J. Holmes has been of great and especial 

 assistance in Dr. Riddle's chief work. She has rendered irreplaceable service 

 in the further work with his data and manuscripts." 



Dr. A. M. Banta reports as follows in regard to his researches 

 concerning additional strains of sex intergrades in Daphnia longispina: 



"The most interesting development of the year has been the finding of sex 

 intergrades in additional lines of Daphnia longispina. 



"In addition to the sex-intergrade strains of Simocephalus verulus and the 

 intergrade strains of Daphnia longispina reported a year ago, intergrades 

 have been found repeatedly in the plus strain of No. 768. Further, sex 

 intergrades have occurred in the strain of No. 768 kept in a dark closet, in 

 the minus strain of No. 768, in No. 897, and in No. 898. Of the six strains 

 of Daphnia longispina reared in the laboratory during the past year, No. 

 899 alone has failed to yield sex intergrades. 



"Two additional probable occurrences of sex intergrades are of interest in 

 this connection: (a) In 1915, along with a few males found in two strains of 

 Daphnia longispina, were a few individuals then considered gynandromorphs. 

 They were rather weak individuals when found and failed to produce young. 

 From descriptions I am now convinced they were intergrades. (h) R. de la 

 Vaulx has found what he called 'androgynous females,' or gynandromorphs, 

 in Daphnia atkinsoni. From this account thej^ clearly appear to have been 

 sex intergrades. 



" These extensions of the known occurrences of sex intergrades among 

 Cladocera indicate that a condition of sex intergradeness in Cladocera is 

 less unusual than was at first supposed; that maleness and femaleness are 

 even less exclusive phenomena, so far as indicated by morphological charac- 

 ters in Cladocera, than was believed. With the relativity of sex so emphati- 

 cally shown in hybrid pigeons, in hybrid moths, and in different species of 

 Cladocera (see report for 1917), one wonders if the relativity of sex ends with 

 pigeons, gypsy moths, and water fleas. There seems every reason to think 

 it does not. 



"We are coming to the time when it would seem imperative to revise our 

 notions of the fixity of sex. The clear cases of sex intergrades or sex inter- 

 mediates just referred to seem no more nor less illustrations of the relativity 

 of sex than one sees in the 'crowing hen' and the 'sitting cock' or in the 

 masculine woman and in the man who in almost intangible physical charac- 

 teristics, in speech, in dress, in tastes and habits of behavior, and in methods 

 of thought reveals himself as lacking in something which makes for the 

 fully equipped male and as possessing qualities ordinarily recognized as 

 characteristics of the female. 



"Further, it does not seem necessary to suppose that relativity of sex is 

 restricted to cases in which its very conspicuousness forces itself upon our 

 unwilling attention in opposition to our fixed conceptions of maleness and 

 femaleness as complete, opposed, and mutually exclusive phenomena. 

 Indeed the more reasonable supposition may be that sex is always relative; 

 that while most sexual individuals of whatever species are prevailingly male 

 or prevailingly female, every individual may have something of the other 

 sex intermingled with the prevailing sexual characters." 



