/t.", '2 



l\ idM'KliKNd', IMKIlWTMiN.M.i; lil': l,l'.\Kili,ll K. 



.•iniimiils (111 llic slyli' IVdiii llic liisl i)|iiMiiiiL;- ni' llic llowcr. ;iimI \\\\~^ iiiililVc- 

 rciilly wlicllicr llic Icnialc |i:iiriil Ijc r|il;inil m- l'ii^x pi i;iii. Wlirii i-illnT oT 

 thèse liave llieir sell-pullen siiiiilarly iiiixed willi pollen lidiii Ihr l',, llie pcricii 

 lagc of vieil! istemhryos foiinedli.e., F./- plant s), rises loaiimil Iwenly-live pereeiil. 



3.5 



II-. '-'. — I,. 



't.O 



iiii (>r iii< 



Tiiis f^rcalcr iiireclixc-capalpilil y ot llie F, polliMi ccmld lie a(lei|ualel\ explai- 

 iieil il' tlie imillil'arioiis (lilVeremes iii composition belween (lie niale gamele 

 niielei et tiie varions F; grains entaileil a eorrelated seri(>s oi' diU'erenees in 

 e. g., the gi'owth-rales, cl' the pollen lulies aiising Iherefrotn. Tliis very plau- 

 sible view is worlliy of further slndy, siiiee il is olivious tliat it enlails llie pend- 

 iiig discovery of at least one metliod of dilTereiilialing llie maie gamele licfoi-e 

 ferlilization : siieli diUerenlialion is a mallei' ol' the grealest iiii|)oilanee. and i^ 

 moreovcr one wliieh miglit he of considérable économie niilily. 



The matter cannot be discussed further hère, bnl il slimild lie iminied oui 

 Ihat the phenomenon sliould be niost easily recogiiisable in (lie pollen of speeies- 

 hybrids, where, on account of Ihe large number of dilTerenlialiiig charaeters in 

 tlic parents, the gamètes arc correspondingly various, and any physiologieal 

 funclion of the pollen tube should bave a correspondingly wide range of varia- 

 lion. On Ihe olber band, the F.r, populalions resulling froni such mixed-polli- 

 iialions will re(|uire specially delailed sliidy, and eomparison with simple F./-. 

 families derived from crossing of F, q' upon I' 2 . 



riie wrilcr made an unsuccessful altcmpt to breed a iion-crossable llower. 



