42 THE PLANT WORLD. 



FIRST CROSSES BREEDING TRUE. 



Hybrids of the first generation which breed true offer 

 many difficulties in the theoretical explanation of hybridiza- 

 tion and hence most writers on genetrlcs are disposed to doubt 

 their existence. Bateson in a recent summary says: "Of the 

 considerable number of examples In which this phenomenon 

 has been alleged to occur, few have been satisfactorily ob- 

 served on a large scale. The evidence is not in my opinion In 

 any case so cogent that it can be accepted without hesitation, 

 and If genuine examples exist, they must be exceedingly rare, 

 for I do not know of any that have been attested by adequate 

 evidence since the modern methods of genetic research have 

 been In use." 



In addition to the earlier evidence presented by DeVrles 

 on this matter he has recently published an article in which 

 he gives results in which all of the hybrids of the evening 

 primrose in the Onagra group were found to be fixed and 

 constant. (Bot. Gazette, Dec, 1907.) A fixed hybrid was 

 produced by the writer by pollinating O. Lamarckiana by O. 

 cruciata several years ago, and this form has been found 

 constant in the several generations which have since been 

 grown under cultivation. — D. T. McD. 



The influence of pollination on the respiratory activity of 

 the gynaeceum, by Jean White, is the subject of an Important 

 paper in Annals of Botany, for October, 1907. The author 

 studied species of Eucalyptus, Fuchsia, Pelargonium, Digi- 

 talis, Begonia, Tecoma, Tropaeolum, Cheiranthus, Antirrhi- 

 num, Anemone, Lilium, Canna and Agapanthus. Among 

 the important results the writer found that the pollinated 

 material of Pelargonium produced 5.8 times as much carbon- 

 dioxide as the unpollinated, Cheiranthus 2.0 times as much, 

 and Antirrhium 2.6 times as much by weight. Throughout 

 the experiments with few exceptions, which were mainly 

 among the Monocotyledons, the respiratory activity of the 



