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ROYAL HORTICULTURAL SOCIETY. 



do not show the slightest trace of any development of the seed 

 though abundant opportunity was afforded, either in the way of 

 artificial application, or through the natural agency of insects in 

 the open air. The female catkins of the above-mentioned hybrids 

 of S. triandra wither quickly after expansion, and fall off prema- 

 turely, those of 8. longifolia, on the contrary, are apparently 

 luxuriant, ripen and burst, but they contain no seed. As the 

 male plants of S. (triandra + viminalis) and S. longifolia are dis- 

 tinguished by a far advanced irregularity of pollen, a certain 

 connexion between the imperfect formation of the male and female 

 organs of this hybrid is not to be mistaken. Other examples 

 might be adduced. In the greater number, indeed, of female 

 hybrids of willows there is, in comparison with the pure species, 

 a less degree of fertility, which appears only in the diminished 

 number of seeds ; while many hybrid willows, examined superficially 

 appear to be quite as fruitful, if attention is paid only to the 

 woolly contents of the capsules. Even in these, Wichura believes 

 that an attentive examination would show a diminished number 

 in confirmation of G-sertner's assertion " that even the most 

 fruitful hybrids yield constantly a smaller number of seeds than 

 the parent species fertilized with their own pollen." » 



But not only in the organs of reproduction, but also in their 

 vegetation, hybrids exhibit many phenomena by which they are 

 more or less decidedly distinguished from pure species. Kcel- 

 reuter and Graertner both agree that the greater number of the 

 hybrids which they raised artificially were distinguished by rank- 

 ness of growth. The plants were taller than their parents, spread 

 more on every side, had a longer duration (being biennial or 

 perennial when the parents were annual or biennial), were more 

 capable of withstanding cold, and blossomed more freely, luxu- 

 riantly, and precociously than the parents ; something of which 

 appears also from Naudin's experiments, so far as extreme luxu- 

 riance is concerned, as witness his hybrid Miralilis. On the con- 

 trary, Gsertner speaks of other hybrids which succeeded only in 

 very favourable weather, and were intolerant of cold. These were 

 hybrids whose parents were only slightly related, and whose 

 seedlings were delicate from the first. 



Similar examples occur amongst hybrid willows ; but luxuriant 

 growth is by no means the normal character. It is doubtful 

 whether the hybrids of S. caprea and viminalis, S. cinerea and 

 incana, with their tall and spreading habit, are to be reckoned as 

 examples, since they are to be explained by the union of tendency 



