350 Agricultur, Horticultur, Forstbotanik. 



that the hybrid plants be self-fertilized , from the fact of xenia, it 

 is then possible to distinguish the ears which have grown from pure 

 dominants and thus secure a pure strain in the second generation. 



III. Inbreeding in Corn. p. 419—428, pl. 40. It is held in 

 accordance with Shull that the self-fertilization of corn simply 

 isolates "biotypes" and that these by themselves are less vigorous 

 than the "hybrids" continually formed in nature by intercrossing. 

 On this hypothesis it is believed that the loss of vigor in self-ferti- 

 lized corn plants is not in the nature of a degeneration and ceases 

 as soon as the biotype is isolated. Ears that had been self-fertilized 

 for 3 years produced plants that showed "no sign of degeneration", 

 though less vigorous than the crossed type, a result at variance 

 with the experiments of de Vries, Webber and Shamel. The 

 tendency to save crossed plants on account of their greater jield 

 explains the usual fäilure to isolate biotypes. 



IV. Some Essential Points in Potato Breeding. p. 429 — 

 452, pl. 51. Among 721 varieties under Observation only 31 showed 

 no sign of flowering. The non-flowering varieties all appeared to 

 be ill-adapted to the soil and climate, a result that does not Sup- 

 port the theory that organisms axesually propagated return to sexual 

 reproduction when in a starved condition. 



An efifort was made to force the formation of seed by preven- 

 ting the growth of tubers, but with no definite result. The pollen 

 appears to be in the best condition on the second day of blooming 

 and band poUinations succeed best when made in the early mor- 

 ning. The flowers produce no nectar and the small amount of 

 natural pollination is anemophilous and a majority of the fruit is 

 thought to be self-fertilized. With the varieties "Chenango" and 

 "Keeper" self-pollinations were more successful than crosses. 



The pollen grains may be either smooth and spherical or they 

 may have from one to live protuberances. A pollen tube germinates 

 from each of these protuberances, showing these grains to be mul- 

 tinucleate. Hand pollinations were found to be more successful in 

 varieties that produced a high percentage of these multinucleate 

 pollen grains. The fruit is less likely to drop if a number of flowers 

 of the same infiorescence are fertilized, and as the Stigmas dry 

 after the first pollination, it is essential to apply an abundance of 

 pollen, and the value of the multinucleate pollen grain is here sug- 

 gested. An effort was made to determine the extent of correlation 

 of different characters; a decided correlation was found in only one 

 case, that of dark purple stems with dark purple tubers. 



G. N. Collins. 



Gabrieli, S., II Mandorlo amaro considerato sotto l'as- 

 petto filogenetico, culturale e chimico. (Atti R. Istit. 

 Incoragg. Napoli. Ser. VI. Vol. IV. p. 17. 1907.) 



La culture de l'Amandier date d'une epoque tres reculee; 

 il est tres difficile par consequent d'indiquer sa patrie. L'Aman- 

 dier sauvage est Signale par Korsinsky de la r^gion caucasienne 

 et de l'Armenie et de l'Algerie par Trabut; mais l'auteur pense 

 que dans les deux cas il ne s'agit pas de plantes vraiment spotanees 

 mais plutöt de plantes subspontanees. II admet sa provenance Orien- 

 tale et accepte l'hypothese de de Candolle qui lui attribue comme 

 patrie la region du Golfe Persique, ne pouvant pas admettre que 

 cet arbre si sensible aux basses temperatures ait pu prendre origine 

 dans une region ä climat continental. II passe en revue les diffe- 



