132 



ExjicriiiK >it ■'). All cxjH'rinii'iil ii'ilh irhcal alone, jihtciil under a hell 

 (jhiss ( tcloher J'!. — ()c[i)\H:v '27. Sonic \viii!j,('(l spcciiiiciis, l»ut. no youn*;'. 

 NovciiilxT I. Mostly wiiif^cil fcMKilcs. November ."]. Incrcasinfi; iiuinhor 

 of youn^-, many of which have waiKhM'cd to the top of the fi;las,s. Novem- 

 ber 5. Botli wiiiiiicss and winded specimens pi'cscnt, l)Mt not mnch 

 chanjie in numbers. November 7. l'\'\ver winded than i)reviously. 

 Wingless ones about the same. November S. Winged specimens have 

 gone. Very few wingless remaining. NoN'cmber 10 and 12. A few 

 wingless specimens were detected, but b\' the l.'ith all wen^ gone. 



Experiment fi. A irimjed Aphis nididis Isoldtcd on tvlieat under a 

 bell glass November /'>', i/oiiikj rorti being hd rod need December S. — Novem- 

 ber 14. (lives birth to one young. Novembei- Ki. Young still living. 

 November 11). l'\'niale yet living, with rather feel)le young. Noveml)er 

 20. iM'inale still alive, with three young. November 21. A fourth 

 young one alive. Some cast skins show the molting of tlu^ others. 

 November 22. Winged louse still living, and the four young increasing 

 in size. November 24. \'oung lice molted again. The motlier still 

 living. November 2(). l''resh young. WingcMl parent still living. 

 November 27. The winged female and five young living. November 

 29. Winged paixMit. and six young alive, the oldest of these almost 

 full grown. November 30. More young, with the winged female still 

 alive. Deceml)er 1. Wingx^l louse has disappeared, but two of her 

 wingless descendants hax'e each gixcn birth to one young since the last 

 observation. These are of the third generation, counting the winged 

 isolated female as the first. December 8. Apparently fewer than on 

 the 1st, but a lai'ge inimber of young, (irowing corn placed in the 

 eartluMi pot. December I. Some \(m'v young of the third generation 

 are feeding on the corn. December 5. Six wingless, young and old, 

 this morning ar(> inclined to wander from the wheat. ( )ne found creep- 

 ing out under the bell glass. Deceniber (i. Two of th(> young plant- 

 lice on the coi'u. l)ec(Mnb(M' 10. Saw only four wingless plant-lice, 

 three of them full grown. December 12. Moi'c young of the third 

 genei'ation. Some of the oldest of this generation have disapjieared. 

 Only one of the second generation now alive. Decembei- \'.\. Some of 

 the third generation have molted again and seem about full grown. 

 Deceniber 17. Third geiiei-alion uioHimI again, oldest one almost full 

 grown. December IS. Two of the lai'gest of this gcMieration ha\(' dis- 

 appeared. December 1*). ( )nly three of the third generation still ali\-e. 

 December 20. One yoimg of the fourth generation has appeared. .lan- 

 iiary 3. Several of the foui'th generation more than half gi'own. Young(T 

 specimens more mnnerous. January T). 4\vo young of the fifth genera- 

 tion |)resent. .lainiary 7. Moi'e of the fifth generation have appeared. 

 Jamiary 17. \Oung of the sixth gxMieration noted, .lainiary 21. 

 Many young of the sixth generation pres(M>t. January 29. Sixth gen- 



