November 30, 1906.] 



SCIENCE. 



695 



wireless equipment, or one of the several v^ire- 

 less telegraph companies will take the matter 

 up; for although it may not lead to a better 

 understanding of aurora, it might help to the 

 understanding of ' freak distances ' over the 

 wire. C. J. Stuart. 



Montreal, October 29, 1906. 



THE GLACIAL EPOCH. 



To THE Editor of Science: While I much 

 regret having overlooked the references to 

 which Professor Chamberlin calls attention 

 in the first few lines of his communication to 

 Science (October 26, page 531), his further 

 remarks (tending to demonstrate that Dr. 

 Manson's theory is untenable), when consid- 

 ered in connection with the equally modern 

 and equally reliable views of Professor E. W. 

 Hilgard (as expressed in the last paragraph 

 of his paper quoted on page 440 of this jour- 

 nal) afford an instructive illustration of how 

 difficult it is, even for an able and con- 

 scientious investigator, to avoid dogmatism in 

 science. J. M. Schaeberle. 



Ann Arbor, 



October 29, 1906. 



SPECIAL ARTICLES. 



VARIATION IN PARTHENOGENETIC INSECTS. 



If, as the Neo-Darwinians claim, amphi- 

 mixis is the principal cause of variation (of 

 the continuous or fluctuating sort taken by 

 Darwin and Weismann to be the material used 

 by natural selection for species-building), it 

 would seem to follow that much less varia- 

 tion, of this type, should occur among par- 

 thenogenetically produced individuals than 

 occurs among individuals of bi-sexual parent- 

 age. The Neo-Darwinians explain variation 

 as a product of sex and sex as a product of 

 the necessity for variation. 



The variation of bisexually produced indi- 

 viduals is proved by limitless miscellaneous 

 observation and the more recent better com- 

 piled and expressed work of biometricians. 

 But data and facts concerning the variation 

 in parthenogenetically produced individuals 

 are not so readily accessible. In the following 

 paragraphs will be found a summary state- 

 ment of the results of certain observations 



made by several assistants ^ and myself, on the 

 variation exhibited in certain series of par- 

 thenogenetically produced insect individuals. 



It is obvious that a comparison of the varia- 

 tion in agamically produced individuals with 

 that of those of bi-sexual parentage in the 

 same species would be particularly pertinent. 

 And this we have been able to make in the 

 case of the honey-bee. The variation^ of 

 various wing characters (dimensions of wings 

 and vein-parts, modification of venation, num- 

 ber of costal hooks of hind-wing, etc.) has been 

 studied in series of drones (parthenogenetic- 

 ally produced individuals) from queen-laid 

 eggs (and also in series from worker-laid ( !) 

 eggs) and in series of workers, which are of 

 bi-sexual parentage. Among these series are 

 some (both of drones and of workers) in which 

 the individuals were taken directly from the 

 brood-cells (just as they were ready to issue) 

 and hence before their exposure to any intra- 

 specific (individual) selection on a basis of 

 their adult characters (among which are all 

 wing characters), and other series made up 

 of actively flying, i. e., exposed individuals. 

 There are also series of drones hatched from 

 worker-laid eggs and reared in worker cells 

 (instead of in the usual larger drone cells), 

 the variation in these series having a special 

 interest because of the possibility of its modi- 

 fication by the extrinsic factor, size of cell. 

 In addition to the bee series the variation in 

 wing characters in a series of parthenogenet- 

 ically produced female plant-lice (Aphididae) 

 has been studied. The studies are all statis- 

 tical and quantitative and have been compiled, 

 tabulated and summarized according to the 

 now fairly familiar methods of biometric 

 variation study. In this note only the baldest 

 statement of results can be made, and their 

 presumable significance suggested. 



Variation in drone {parthenogenetically 

 produced) and worker honey-hees (of hi- 



^R. G. Bell, B. E. Wiltz, A. Wellman and F. 

 Yantis. 



^ Some of these data of variation in the honey- 

 bee have already been published by Kellogg and 

 Bell, ' Studies of Variation in Insects,' Proa. 

 Wash. Acad. Sci., Vol. 6, pp. 203-332, 1904. 



