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THE AMEBIC AN NATURALIST [Vol. XLVIII 



In other words, a high percentage of Beadedness came 

 from flies raised on alkaline food, a low percentage from 

 flies raised on acid food, and intermediate amount from 

 flies raised on fresh food. 



A careful study of Table XXXI will reveal the curious 

 partial sex-linkage of which I spoke on pages 15 et seq., 

 and here, too, the explanation suggested there seems to 

 apply as in other cases of the sort. It is not a little 1 

 peculiar that in all of these food tests this phenomenon 

 should have occurred, though I consider this purely a 

 coincidence. In any case, if we can draw any conclusion 

 at all from its appearance, it would only be that the re- 

 action of the food has nothing to do with the occurrence 

 of the phenomenon rather than the reverse. 



E. The Effects of Relative Temperatures 

 No evident effect was produced by rearing the Fj gen- 

 eration in an ice-chest, but ratios were as varying as when 

 the flies were raised at room temperature. Ratios of 15.4 

 per cent., 19.2 per cent., 10.3 per cent., 20 per cent, of 

 Beaded offspring are examples of those given by broods 

 raised' at low temperatures. The cold does, however, 

 lengthen greatly the larval life and flies were in the case 

 of the brood last mentioned twenty-eight days in hatching. 

 The brood consisted of 312 normal and 77 Beaded-winged 

 flies. 



Similar results were obtained in experiments with 

 heat, except that here the larval life was correspondingly 

 shortened and was at times reduced to eight days. It 

 was not found practicable to keep the flies at higher than 

 30°-33° Centigrade, as they soon died at higher tempera- 

 tures. 



F. The Effects of Darkness 

 Flies were raised in complete darkness and sister 

 broods in full daylight, but no differences appeared in the 

 offspring. Of 484 flies raised in darkness 30 per cent, 

 had Beaded wings. Of 360 flies raised in the daylight, 

 29 per cent, had Beaded wings. This experiment seems 



