534 



SCIENCE 



[N. S. VOL. XXXIII. No. 849 



termites by Holmgren; a similar account of 

 the ants by Forel ; descriptions of the termito- 

 philous coleoptera by Wasmann; a description 

 of a new cricket (Myrmecophila escherichi) 

 which has become termitophilous, by Schim- 

 mer; termitophilous thysanura, myriopoda 

 and coleopterous larvag by Silvestri ; a termito- 

 philous earthworm (Notoscolex termiticola) 

 by Michaelsen. 



W. M. Wheeler 



SCIENTIFIC JOURNALS AND ARTICLES 



The contents of The American Journal of 

 Science for April are as follows : 



"Ionization of Different Gases by the Alpha 

 Particles from Polonium and the Relative Amounts 

 of Energy Required to Produce an Ion," T. S. 

 Taylor. 



"Heat Generated by Eadio-active Substances," 

 W. Duane. 



"Contributions to the Geology' of New Hamp- 

 shire. IV. Geology of Tripyramid Mountain," 

 L. V. Pirsson and Wm. North Rice. 



"Note on a Method in Teaching Optical Min- 

 eralogy," P. W. McNair. 



' ' New Paleozoic Insects from the Vicinity of 

 Mazon Creek, Illinois," A. Handlirseh. 



"Results of a Preliminary Study of the so- 

 called Kenai Flora of Alaska," A. HoUick. 



SPECIAL ARTICLES 



^THE ORIGIN OF FIVE MUTATIONS IN EYE COLOR IN 



DROSOPHILA AND THEIR MODES OF 



INHERITANCE 



The White Eye 

 In cultures of Drosophila ampelophila, that 

 had been closely inbred for a year, a male fly, 

 lacking the red pigment of the eye, appeared. 

 The same stock has continued to produce 

 these white-eyed mutants always of the male 

 sex. A white-eyed father transmits the char- 

 acter to about one fourth of his grandsons, 

 but to none of his granddaughters. In this 

 sense the character is sex limited. The white 

 eye can be transmitted, however, to the 

 females, most readily by breeding any white- 

 eyed male to red hybrids (FJ out of white by 

 red. White-eyed males and females give pure 

 stock. When a white-eyed female is bred to 



any wild male all of the female offspring have 

 red eyes and all of the male offspring white eyes. 

 The result shows that the male-bearing sperm 

 of the wild flies lacks at least one of the factors 

 essential for the production of red eyes. This 

 statement does not mean that the male-deter- 

 mining sperm lacks all of the factors essential 

 for producing red, but only that it lacks one 

 of the factors necessary for the production of 

 red. In fact, it is conceivable that all of the 

 rest of the cell may be equally essential for the 

 production of red, but in the absence of one 

 condition (factor) the red fails to develop. It 

 is in this sense that I understand the use of 

 the word " factor " in inheritance ; and in the 

 same sense one might employ the word " unit 

 character," although the latter word may seem 

 to imply (from usage) that a particular char- 

 acter is represented entirely by some unit in 

 the germ cells. We are not warranted, I be- 

 lieve, in extending to the results of Mendelian 

 inheritance such an interpretation. Since I 

 have discussed elsewhere the mode of trans- 

 mission of the white eyes,' I shall omit further 

 details here. 



The Pinh Eye 



This eye color has appeared at least twice in 

 cultures in no way closely related to the white- 

 eyed stock. It is not due to a cross between 

 red- and white-eyed flies. The color is much 

 lighter and more translucent than red, and ap- 

 pears to contain more yellow. It is seen to 

 best advantage soon after the flies have 

 emerged. Later it becomes darker and casual 

 observation might mistake it for red. As the 

 flies get old the pink changes to a somewhat 

 purplish color, and this change does not take 

 place in the red eyes, so that with experience 

 there is no difficulty in separating the two 

 colors at all stages. No intermediate condi- 

 tion has been seen despite the fact that thou- 

 sands of the pink-eyed flies have be^n ex- 

 amined. 



Pink-eyed males bred to wild red-eyed 

 females produce all reds in the first genera- 

 tion. These flies, inbred, have produced in 

 the second filial generation 3,063 reds to 169 



» Science, July 22, 1910. 



