302 ORIGIN OF SPECIES 



bert. He is as emphatic in his conclusion that some hybrids 

 are perfectly fertile — as fertile as the pure parent-species — 

 as are Kolreuter and Gartner that some degree of sterility 

 between distinct species is a universal law of nature. He 

 experimented on some of the very same species as did 

 Gartner. The difference in their results may, I think, be in 

 part accounted for by Herbert's great horticultural skill, and 

 by his having hot-houses at his command. Of his many im- 

 portant statements I will here give only a single one as an 

 example, namely, that "every ovule in a pod of Crinum 

 capense fertilised by C. revolutum produced a plant, which 

 I never saw to occur in a case of its natural fecundation." 

 So that here we have perfect or even more than com- 

 monly perfect fertility, in a first cross between two distinct 

 species. 



This case of the Crinum leads me to refer to a singular 

 fact, namely, that individual plants of certain species of 

 Lobelia, Verbascum and Passiflora, can easily be fertilised by 

 pollen from a distinct species, but not by pollen from the 

 same plant, though this pollen can be proved to be perfectly 

 sound by fertilising other plants or species. In the genus 

 Hippeastrum, in Corydalis as shown by Professor Hilde- 

 brand, 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 hybridised 

 much more readily than they can be fertilised by pollen from 

 the same individual plant ! To give one instance, a bulb of 

 Hippeastrum aulicum produced four flowers ; three were fer- 

 tilised by Herbert with their own pollen, and the fourth was 

 subsequently fertilised by the pollen of a compound hybrid 

 descended from three distinct species : the result was that 

 "the ovaries of the three first flowers soon ceased to grow, 

 and after a few days perished entirely, whereas the pod im- 

 pregnated 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. 



