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THE AMERICAN NATURALIST [Vol. XLIX 



discussion is concerned, the conclusions in general have 

 largely been assumptions based on little or no evidence. 



It was Weismann (76) who was evidently the first to 

 definitely express the importance of sex in producing 

 variations, an idea to which he consistently held in his 

 subsequent papers, while Nageli ('84), Strasburger 

 ( '84), Hatseheck ( '87), Haycraft ( '95), etc., believed like- 

 wise on theoretical grounds that variability was reduced 

 by amphimixis. 



The first paper presenting tangible evidence upon the 

 subject was that of "Warren ('99) who found that par- 

 thenogenetically produced Daphnia magna were slightly 

 more variable as measured by the "Standard Deviation" 

 which had a value of 2.95, than the mothers whose ' ' Stand- 

 ard Deviation" was 2.22. The small number utilized, 

 96 in the first instance and 23 in the second instance, to- 

 gether with the fact that the mothers represented a se- 

 lected class, only those Daphnia producing young being 

 included, did not allow placing much reliance in the re- 

 sults. Warren ( '02) compared 60 parental aphids {Eya- 

 lopterus trirhodus) and their 368 offspring as well as a 

 series from 30 aphid grandparents and their 291 grand- 

 children. The variability was found in a comparison of 

 grandparents and grandchildren (parthenogenetic) to 

 have slightly decreased in respect to frontal breadth and 

 considerably increased in respect to length of right 

 antenna, but again objections similar to those in the pre- 

 ceding paper render the conclusion of little value, as 

 "Warren himself observed. 



Casteel and Phillips ( '03) measured drones and workers 

 of Apis mellifica, the honey bee, selecting individuals at 

 random from different colonies, and tabulating classes 

 and frequencies without, however, a further application 

 of biometrical methods. The "range of variability" was 

 found to be greater in the drones than in the workers. 

 Lutz ( '04) criticized the methods utilized in the paper, 

 nevertheless variation as measured by the standard devia- 



