50 A TREATISE ON HORSE-BREEDING. 



In commenting upon this aspect of genesis, 

 Herbert Spencer says: 



Remembering the fact that among the higher classes of 

 organisms fertilization is always effected by combining the 

 sperm-cell of one individual with the germ-cell of another, 

 and joining with it the fact that among hermaphrodite 

 organisms the germ-cells developed in any individual are 

 usually not fertilized by sperm-cells developed in the same 

 individual, we see reason for thinking that the essential 

 thing in fertilization is the union of specially-fitted portions 

 of different organisms. If fertilization depended on the pecu- 

 liar properties of sperm-cell and germ-cell, as such, then in 

 hermaphrodite organisms it would be a matter of indiffer- 

 ence whether the united sperm-cells and germ-cells were 

 those of the same individual or those of different individuals. 

 But the circumstance that there exist in such organisms 

 elaborate appliances for mutual fertilization shows that un- 

 likeness of derivation in the united reproductive centers is 

 the desideratum.* 



After explaining at some length the apparent 

 contradiction of this theory which is found in 

 plants that are self-fertilizing, Mr. Spencer fur- 

 ther remarks: 



There is reason to believe that self-fertilization, which at 

 the best is comparatively inefficient, loses all efficiency in 

 course of time. After giving an account of the provisions 

 for an occasional, or a frequent, or a constant crossing be- 

 tween flowers, and after quoting Prof Huxley to the effect 

 that among hermaphrodite animals there is no case in which 

 "the occasional influence of a distinct individual can be 

 shown to be physically impossible," Mr. Darwin writes: 

 "From these several considerations, and from the many 

 special facts which I have collected, but which I am not 

 here able to give, I am strongly inclined to suspect that, 



* "Principles of Biology," Vol. I, p. 279. 



