Morphologie etc. — Varietäten etc. 19 



La tecondation n'est pas necessaire au developpement du cöne 

 mais eile en active la croissance. 



Les differentes caracteristiques de la structure du cöne qui 

 servent ä classer les sortes de Houblon, sont susceptibles de varier 

 sous des influences diverses, et pas plus d'ailleurs que les caracte- 

 ristiques de la Vegetation, elles ne peuvent suffire ä definir les 

 Varietes de Houblon; en consequence, malgre les innombrables 

 sortes de Houblon cultive qu'on a decrites et figurees, l'espfece H. 

 Liipiihis n'en reste pas moins tres homogene. 



De cette etude, on peut enfin tirer des conclusions d'ordre plus 

 general. 



10. A propos du detenninisme du sexe, les experiences faites 

 avec le Houblon japonais montrent qu'il est possible, dans des con- 

 ditions experimentales realisables ä volonte, de modifier, ä partir 

 de la germination, le sexe des plantes dioiques, mais que ces chan- 

 gements de sexe sont d'une part, limites ä une assez faible Propor- 

 tion d'individus et, d'autre part, ne sont jamais complets ni definitifs. 



2'^. Les phenomenes consecutifs ä la pollinisation du Houblon 

 commun par du poUen d'especes tres differentes etablissent la pos- 

 sibilite chez les vegetaux, de developpements abortifs du gamete 

 femelle, avec ou sans amphimixie, tout ä fait comparables ä ceux 

 qui ont ete observes apres fecondation entre especes ou genres 

 differents d'Oursins ou de Batraciens et oü l'arret de croissance 

 est du soit ä l'absence de l'apport de substance chromatique male, 

 soit ä la formation d'une association chromatique par trop hete- 

 rogene. Jongmans. 



Collins, G. N. and J. H. Kempton. Inheritance of endo- 

 sperm texture in sweet X waxy hybrid s of Maize. 

 (American Naturalist. XLVIIL p. 584-594. 1 Fig. 4 Tab. 1914.) 



In a previous publication the first and second generation of 

 Grosses between sweet and waxy varieties of maize were reported. 

 It is now possible to add the results of the third season, which to 

 some extent afford a test of the explanation proposed in the first 

 publication. 



The immediate (xenia) result of crossing varieties of maize 

 having sweet and waxy endosperm was the production of seeds 

 with a horny endosperm resembling that of ordinary field varieties. 

 In the second xenia generation all the ears contained seeds of the 

 three classes, sweet. waxy and horny, in fairly definite ratios. The 

 data were arranged in accordance with the Mendelian formula cor- 

 responding most nearly to the observed numbers. 



The third generation, like the second, gave results sufficiently 

 close to dihybrid ratios to render unprofitable the assumption of 

 more complicated ratios. There are, however, deviations from the 

 expected numbers of too great magnitude to be ascribed to chance. 



The ratios of waxy to non-waxy seeds were regulär as far as 

 the conditions of the experiment could determine, except Ibr a 

 slight excess in the number of waxy seeds in nearly all the ears 

 in which all three classes appeared. A deviation in number of waxy 

 seeds as large as that shown in the total would not be expected 

 to occur as the result of chance more offen than once in one thou- 

 sand times. 



The ratios between sweet and horny, while aproximating the 

 predicted ratios, show numerous irregularities. Wherever there is 



