358 Experimental Zoology 
been found that virgin eggs produce males, but von Siebold ob- 
tained 13 females among 1700 males; he thinks these may have 
been introduced with the food. ‘Other observers have obtained 
only males.” 
In another group, the gallflies, Cynipide, females appear 
in preponderating numbers and reproduce by parthenogenesis 
in one generation at least. Males in some forms are of the rar- 
est occurrence, and have never been found in some species. 
It has been observed, however, that in some species the eggs 
produced by the parthenogenetic females give rise to insects, 
both male and female, quite different in appearance from the 
parthenogenetic generation. The complete life histories of 
some of these species have been given on page 268 in describ- 
ing the formation of galls. According to Adler, not more than 
2 percent of males appear in the sexual generation of Rhodites 
rose and R. eglantene. The female of Phromali lays her egg 
in the caterpillar of Vanessa urticee. In several cases caterpillars 
were reared, which were kept uncontaminated, and an unfer- 
tilized female of Phromali deposited eggs in them. When the 
flies emerged from the pupa there were found in one case 124 
males, in another case 62 males, in a third case 75 males and 5 
females, and in a fourth case 45 males and 4 females. Thus 
while the unfertilized eggs of this species produce males, occa- 
sionally females also appear. 
These cases serve as a warning not to insist with too much 
positiveness on the view that in the bee unfertilized eggs always 
produce males, since they show that exceptions to such a rule 
may sometimes occur. 
LITERATURE, CHAPTER XXIII 
Cameron. Monograph of Phytophagus Hymenoptera. 1882-1884. 
CasTEEL, D., and Puitiips, E. Comparative Variability of Drones and 
Workers of the Honey Bee. Biol. Bull. VI. 1903. 
Dicxet, F. Das Prinzip der Geschlechtsbildung. Darmstadt. 1898. 
Meine Ansicht iiber die Freiburger Untersuchungsergebnisse von Bien- 
eneiern. Anat. Anz. XIX. gor. 
Ueber Petrunkewitsch’s Untersuchungsergebnisse von Bieneneiern. 
Zool. Anz. XXV. got. 
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