FERN GROWING 13 



ments referred to previous crosses as otherwise accounting 

 for the variation. At last the crossing of the varieties of 

 Ferns became an acknowledged fact ; but, strange to say, our 

 authorities, who could not clearly see that the peculiarities of 

 two English varieties had been combined in one and the 

 same plant, were at length convinced by seeing these pecu- 

 liarities in a foreign Fern.* 



Twenty years ago Colonel Jones, on visiting the author's 

 Fernery, was shown a number of seedling Ferns that had 

 been sown together, in order to obtain a cross of two species, 

 as this was thought would prove an answer to those who 

 still looked upon former evidences with doubt. This caused 

 Colonel Jones to take up the subject, and to repeat the 

 author's experiments in identically the same manner. It was 

 thought, as there had been no previously known variety of 

 a cruciate Aspiducni aculeatum, that if spores of a cruciate 

 Aspidium angulare were sown with a dense- fronded Aspidium 

 aculeatum, a cruciate Aspidium aculeatum might be the result. 

 This was accomplished, and ought to be an argument far 

 stronger than the mere crossing of two varieties of the same 

 species ; but here again the author had to meet the expressed 

 doubt of a number of botanists as to Aspidium, aculeatum being 

 distinct from Aspidium, angulare as a species. As mules are 

 more or less sterile, the test of a species ought to be that of 

 sterility. The author crossed the swan goose with the Canadian 

 goose, also the swan goose with the ordinary goose, and the 

 progeny lived many years, and there were eggs laid each year, 

 but no young were ever hatched. The author's father had 

 hybrids between the canary and the linnet, but they never laid 

 fertile eggs. The mule between the ass and the horse is called 

 sterile, but there can scarcely be absolute sterility. It may be 

 twenty thousand to one against the production of offspring 



* The late Sir William Jackson Hooker had, however, partly acknowledged to the 

 Rev. M. J. Berkeley that the example he had sent him did look like a hybrid. 



