Chap. VIII. DEGREES OF STEKILITY. 237 



This case of tlie Crinum leads me to refer to a singular fact, 

 namely, that individual plants of certain species of Lobelia, 

 Vcrbascuni, and Passillora, can easily be fertilized by pollen 

 from a distinct species, but not by pollen from the same; plant, 

 though this pollen can be proved to l)e perfectly sound by fer- 

 tilizing other plants or species. In the genus llippeastrum, in 

 Corydalis as shown by Prof. Hildebrand, in various orchids as 

 shown by Mr. Scott and Fritz Mliller, all the individuals are in 

 this })eculiar 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 jiollen from the same individual plant ! To 

 give one instance, a bulb of llippeastrum aulicum produced four 

 flowers ; three were ferlilizod 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 " the ovaries of the first three 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 experi- 

 ments during many y(iars, and always with the same result. 

 With those plants in which certain individuals alone fail to be 

 fertilized by their own pollen, though thej^ appear cjuite healthy 

 and although both ovules and pollen are perfectly good with 

 reference to other species, yet they must be in some way in an 

 unnatural condition. Tliese 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 ])recision, deserve some notice. It is no- 

 torious in how complicated a manner the species of Pelargo- 

 nium, Fuchsia, Calceolaria, Petunia, Rhododendron, etc., have 

 been crossed, yet many of these hybrids seed freely. For in- 

 stance, Herbert asserts that a hybrid from Calceolaria integri- 

 folia and jilanlaginea, species most widely dissimilar in general 

 habit, "reproduced itself as perfectly as if it had been a natu- 

 ral species from the mountains of Chili." I have taken some 

 pains to ascertain the degree of fertility of some of the complex 

 crosses of Khod(jdendrons, and I am assured that many of thcrn 

 are perfectly fertile. Mr. C. Noble, for instance, informs mc 

 that he raises stocks for grafting from a hvbrid between Rhod. 

 Poiifieiiin and Catawbiense, and that this hybrid "seeds as 



