G2 



EOYAL HORTICULTURAL SOCIETY. 



G-sertner believed that in such combinations, amongst many 

 individuals resembling the hybrid, some plants would occur which 

 reverted very nearly to the maternal, or less frequently to the 

 paternal type. No such reversions, however, occurred in the 

 course of "Wichura's experiments. Particular individuals showed 

 indeed many variations, but no reversion. He believed, therefore, 

 that the pollen of either parent must have had access without 

 GrSBrtner's knowledge ; and Mr. Darwin thinks it probable that 

 the instances alleged by Naudin were due to the circumstance of 

 his plants being cultivated. "Wichura had no opportunity of exa- 

 mining the truth of the fact asserted by both Kcelreuter and 

 G-sertner, that hybrids prefer the pollen of one of the parents to 

 their own, or that the pollen of some strange species may make 

 the pollen of the hybrid powerless, though he thinks both state- 

 ments quite probable. He remarks, moreover, that his quinary 

 and senary hybrids are quite new in the history of hybridization. 

 He believes that the possibility of still higher combination is only 

 prevented by the constantly increasing sterility of the produce. 

 The senary hybrid whose formula is given above was still so 

 fruitful that it would scarcely refuse union with an heterogene- 

 ously combined senary, ternary or quaternary hybrid, while the 

 other senary hybrid, between a quaternary of Salix Lapponum and 

 silesiaca □ purpurea, viminalis Q,smd fertilized with an arti- 

 ficial hybrid of caprea □ and daphnoides O, and then finally fer- 

 tilized with pure daphnoides O, did not give an opportunity of 

 carrying the experiment further, inasmuch as all the plants pe- 

 rished before they produced flowers. 



Impregnation between two quaternaries failed as stated above, 

 in consequence of the far advanced sterility of the female plant. 

 He doubts, moreover, whether it is possible to raise a hybrid of 

 the sixteenth degree between two octonaries. He has nothing to 

 say as regard willows in confirmation of Grsertner's remark, that 

 while species will not combine with some other species, they will 

 do so with a hybrid of that species, as, for example, Nicotiana 

 glutinosa, Tabacum, and Langsdorfii, will not combine with jY". 

 rustica, though they will do so with a hybrid of JV. paniculata and 

 rustica. 



"We now come to a very important chapter on the imperfect 

 nature of hybrids. Our author divided his experiments into two 

 series, successful and unsuccessful. There are, he says, certain 

 degrees of success, which, however, cannot be used as the stepping- 

 stones for a new division, since they pass into each other, 



