Nos. 622-623] THE SEXES IN THE APHID 



513 



Experiment 298.— This line was derived from the 

 female as Experiment 299, but was reared in the £ 

 house. See Table V. 



TABLE V 



,y Produced Line of j 



•ted in Table IV i 



Sept 



Sr],r. 7-Sopt. 1 



second I Sep1 " " 



Third Sepi 



First Sepl 



Second Sep 



Third Sei 



First Ocl 



Experiment 270.— The stem mother of this line hatched 

 from a fertilized egg that was laid in the greenhouse in 

 November and hatched in January. In March and April 

 the line passed through a sexual phase, but a small num- 

 ber of viviparous females were produced during this 

 period and by them the parthenogenetic line was con- 

 tinued. The families were not fully recorded until the 

 latter part of May. Table VI includes only the records 

 beginning May 28. Nine generations are there recorded 

 as if an uninterrupted line, but an explanation is neces- 

 sary. In the midst of the fifth generation the aphids 

 began to die in large numbers for an unknown reason. 

 In a few days every aphid out of hundreds was dead. 

 Fortunately two or three aphids were found on a dis- 

 carded plant in the greenhouse. Since only this one line 

 had been reared in the greenhouse up to that time I felt 



