PARTHENOGENETIC PURE LINE OF APHIS AVENGE FAB. 



nymphs were of both forms (the wingless and winged), and in 

 every instance their young gave only normal adults, and had so 

 far as could be ascertained had normal reproductive powers. I 

 shall here record some data obtained in regard to these paedo- 

 genetic nymphs. 



One of the first paedogenetic individuals observed was 3195. 

 This nymph was of the winged form and never passed beyond the 

 last nymphal stage. It was born from 3^5 along with 13 other 

 young. It reached its final nymphal form at the time that two 

 of its sisters reached their normal maturity. This paedogenetic 

 nymph gave birth to 8 young the first day of reproduction, 4 

 the second, none on the third and fourth days, and was killed on 



FIG. 19. Psedogenetic nymph of Aphis avence Fab. A. 32410, a paedogenetic 

 nymph of the wingless form. B. 115410, a paedogenetic nymph of winged form. 



the fifth day. Of the 12 offspring left, 3 reached maturity. 

 They were normal wingless forms, and differed in no perceptible 

 way from the many other wingless forms at hand. These three 

 normal adults each gave many young, which, however, were 

 not reared to maturity. 



Another paedogenetic nymph to appear was 3 24 io (see Fig. 19, 

 a), which was a paedogenetic third nymph of the wingless form. 

 It was one of the 12 offspring of 323!, a normally winged adult. 

 Of the ii sisters of this paedogenetic form, 10 reached maturity, 

 and all proved to be normal wingless forms. This paedogenetic 

 nymph gave birth to 3 young before it was killed. These young, 

 however, were discarded because of lack of time to care for them. 



