118 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
Dendrobium, Disa, Epidendrum, Lelia, Uelio-Cattleya, Masdevalla, 
Phalenopsis, Odontoglossum, Thunia, and Chysis. © 
While in other natural orders we have fertile hybrids in Cotyledon, 
Begonia, Quercus, Gladiolus, Vitis, Cereus, Viola, Canna, Brassica, 
Nymphea, Primula, Lamium, A%sculus, Berberis, Mirabilis, Salix, 
Mentha, Passiflora, and Fuchsia. 
On the other hand, we have those genera whose hybrids, so far as 
experiments have yet been made, are all absolutely infertile. After a 
careful search I have only been able to find four of these—namely, Ribes, 
Polemonium, Digitalis, and Papaver—and in none of these have many 
experiments been made. 
To my mind, negative results, though useful in their way, are never 
safe guides to follow. I have observed many cases in the Orchidez where 
again and again certain species have refused to cross, yet at another time, 
and under other conditions, quite unexpectedly have produced fertile seeds ; 
and I think that one may reasonably expect even these four recalcitrant 
genera to produce fertile hybrids in the course of time.* 
In regard to the ninety genera which have produced fertile hybrids, it 
may possibly be argued that many of them are not true hybrids, because 
they have been raised from closely related species; but even if this be 
eranted, what about the numerous fertile hybrids from very distinct 
species? For instance, the species of Leelia (Lindl.) and Cattleya (Lind1.) 
respectively are still classed as distinct genera by our best botanists; and 
I think that the most easy-going systematist would admit them to be 
distinct species, yet hybrids raised between these two genera are very fertile. 
But perhaps the best practical proof of the fertility of hybrids is the 
numerous hybrids raised in gardens, of many generations, from several 
species. 
(1) For instance, fertile hybrids have been raised by Messrs. Sutton & 
Sons, of Reading, between Solanum tuberosum and §. Maglia, forty-one 
seedlings being raised from two hybrid plants of the first generation. 
(2) Cytisus x preecox, a hybrid between C. albus and C. purgans, seeds 
freely in my garden, and many plants have been raised in nurseries ; 
these are the second generation of two species. 
(8) As mentioned in another part of this paper, I have raised 500 
plants from seeds of Berberis x stenophylla, itself a hybrid between the 
two species B. Darwinii and B. empetrifolia. 
(4) Mr. James has raised a large batch of seedlings from five hybrid 
Senecios, themselves the product of S. cruentus and 8. Heritieri. 
(5) Scilla bifolia and Chionodoxa Lucilliz cross naturally in gardens, 
and their hybrids, Chionoscilla x Alleni, seed very freely. 
(6) Some of the best forms of Narcissus in gardens are the result of 
hybrids between N. poeticus and N. obvallaris, recrossed with one or other 
of the parent species. 
(7) Our fine garden Strawberries of the present day have been raised 
from many generations, of two species at least, viz. Fragaria virginiana 
and I’. chiloensis, and probably in some cases, such as the variety ‘ St. 
Joseph,’ from F. vesca alpina. 
* Since the above paper was written, M. Vilmorin, of Paris, tells us that he ne 
succeeded in obtaining fertile hybrids in Papayer. 
