No. ii-2'>] i> i/r/7/7-;vor,/- \7->/s AXD ( n\ I i; 133 



in Apoiettix show from small to considerable percentages 

 of crossing-over. The discovery of crossing-over, with 

 the further disclosure that these forms breed partheno- 

 gcnetically, as well as bisexually, prompts me to submit 

 a preliminary report in advance of a more extended 

 presentation of the data and ilhistrations whicli can not 

 be made ready this year. 



The Adams fund has cared for tlic .'xpciiscs. niid T 

 have had the generous and oiii'ii-iiiiiidcd sni>])oit of di- 

 rector, now president, W. ^I. .lafdiiic Mr. A. \\'. Bel- 

 lamy gave effectual assistaricr (!ui-iii,u llic earlier stages 

 of the experiment. 



Parthenogenesis and Crossin(;-o\ i.h tx iui: Fkm \t.e 

 The discovery of parthenogenesis in Apnh-tiir was 

 the result of attemi)ts at cross-breediiiu" the iiieniiiers of 

 this genus with those of the genus Pf/rah tln. \\ was 

 observed tliat wlien an Apotcfti.r male was used with a 

 Paratetfir female no ])rogeny evei' ri'snlt.'d. hut the 

 female of tlie reeittroeal ga\-e offsjiriiig. exclusively 

 females, and of hei- own e(dor i)attern if she were honio- 

 ZNgous. oi- seu'regated into liei' (M>mi)onents and cross- 

 o\-ers if she wen- hetero/.yu-ons. Then it was soon ascer- 

 tained (s,M' ehai't) that tiie Aimtilhr females which had 

 never been ex[)ost'(l males of an\- kind at any time be- 

 haved in this ]-espe('l i)i-ecisel\- as did thos(^ exposed to 

 Farali'fftr males. Copulation between members of the 

 two genera was ne\'er observed. Conlirming these ob- 



mens for nn- and concluded that on account of structural 

 differences the memliers of the (Uie >J:vo\\\^ could not mate 

 with those of the othei-. 



The chart illustrate, a poitlon ef the .Aprrinn iil -Ahich 

 definitely determin.Ml that parihein^uene^i. nccu,-. It 

 also shows crossin<>'-o\'er in the females, ^^)lhu\in^• the 

 chart, the first' KK female, .'xpo-ed to a I'nnii, 't>> male 

 of strongly contrastinu" jiattei-n, produced Ki ot'fsi>i-ing, 

 all females and of her own pattern. Tliree of these 



