WICRTLRA ON HYBRIDS. 57 



positively injurious, as I know to have been the case in one 

 instance which has come before me. 



XIV. Abstract of Max "Wichura's Observations on Hybridi- 

 zation* By the Eev. M, J. Berkeley, M.A., F.L.S. 



In the former series of this Journal I gave an abstract of Graert- 

 ner's important work on vegetable hybrids ; and a translation of 

 JNaudin's more recent observations appears in the present volume 

 of the New Series, together with some interesting remarks of M. 

 Decaisne's on the effects of intercrossing amongst different va- 

 rieties of pears. Very recently a most instructive memoir ap- 

 peared at Breslau, by Max Wichura, which contains so much 

 weighty matter that a copious abstract cannot fail to be acceptable 

 to our readers. I am indebted to Mr. Darwin for the loan of the 

 book, and have profited by his marginal notes pointing out the 

 principal points of interest. 



Herr Wichura informs us in his preface that he was led to the 

 subject by the fact of his friend Dr. Wimmer having arrived at 

 the conclusion, from numerous observations, that a great part of 

 the doubtful forms in the difficult genus Saliso were hybrids. 

 From a desire to confirm the correctness of this conclusion, of 

 which he was, however, already convinced, he determined to in- 

 stitute a series of experiments with a view to find out what would 

 be the actual results of artificial impregnation in this perplexing 

 genus. These experiments were commenced in 1852, and con- 

 tinued uninterruptedly till 1858 ; but unfortunately, partly from 

 illness and partly from a long absence in Japan, they were dis- 

 continued, and as there seems no probability of their being re- 

 sumed, he has thought it best to publish at once the results of his 

 experiments, comparing them, where requisite, with those of 

 Kcelreuter and Grsertner, and pointing out their connexion with 

 Darwin's views on the origin of species. 



In all experiments on hybridization, the one great desideratum 

 is to exclude the possibility of access of every kind of pollen ex- 

 cept that which is the subject of experiment. As willows have a 

 singular propensity to form hybrids, and are, at the same time, 



* Die Bastardbefruchtung im Pflanzenreich, erlautert an den Bastarden der 

 Weiden : von Max Wichura. Mit zwei. Tafeln. 4to. Breslau, 1865. 



