HYBRIDISM 243 



shown by Professor Hildebrand, in various orchids as shown by 

 Mr. Scott and Fritz Miiller, all the individuals are in this peculiar 

 condition. So that with some species certain abnormal individuals, 

 and in other species all the individuals, can actually be hybridized 

 much more readily than they can be fertilized by pollen from the 

 same individual plant! To give oi^e instance, a bulb of Hippeas- 

 trum aulicum produced four flowers; three were fertilized by 

 Herbert with their own pollen, and the fourth was subsequently 

 fertilized by the pollen of a compound hybrid descended from 

 three distinct species; the result was that "tie ovaries of the three 

 first flowers soon ceased to grow, and after a few days perished 

 entirely, whereas the pod impregnated by the pollen of the hybrid 

 made vigorous growth and rapid progress to maturity, and bore 

 good seed, which vegetated freely." Mr. Herbert tried similar 

 experiments during many years, and always with the same result. 

 These cases serve to show on what slight and mysterious causes 

 the lesser or greater fertility of a species sometimes depends. 



The practical experiments of horticulturists, though not made 

 with scientific precision, deserve some notice. It is notorious in 

 how complicated a manner the species of Pelargonium, Fuchsia, 

 Calceolaria, Petunia, Rhododendron, etc., have been crossed, yet 

 many of these hybrids seed freely. For instance, Herbert asserts 

 that a hybrid from Calceolaria integrifolia and plantaginea, 

 species most widely dissimilar in general habit, "reproduces itself 

 as perfectly as if it had been a natural species from the mountains 

 of Chili." I have taken some pains to ascertain the degree of 

 fertility of some of the complex crosses of Rhododendrons, and I 

 am assured that many of them are perfectly fertile. Mr. C. Noble, 

 for instance, informs me that he raises stocks for grafting from a 

 hybrid between Rhod. ponticum and catawbiense, and that this 

 hybrid "seeds as freely as it is possible to imagine." Had hybrids, 

 when fairly treated, always gone on decreasing in fertility in each 

 successive generation, as Gartner believed to be the case, the fact 

 would have been notorious to nurserymen. Horticulturists raise 

 large beds of the same hybrid, and such alone are fairly treated, 

 for by insect agency the several individuals are allowed to cross 

 freely with each other, and the injurious influence of close inter- 

 breeding is thus prevented. Any one may readily convince himself 

 of the efficiency of insect agency by examining the flowers of the 

 most sterile kinds of hybrid Rhododendrons, which produce no 

 pollen, for he will find on their stigmas plenty of pollen brought 

 from other flowers. 



In regard to animals, much fewer experiments have been care- 



