92 ox VARIETIES, EACES, SUB-SPECIES, AND SPECIES. 



Knight were at issue : tlie latter gentleman denied tliat true 

 hybrids had any power of fecamdation, and only admitted it in 

 sub-liybrids ; and in carrying liis theory out he asserted the 

 Peach to be a variety of Almond, because the Peach-almond, a 

 hybrid derived from the two, could propagate itself by seed. 



In the animal kingdom there are most certainly hybrids which 

 have the power of generation ; the following examples show 

 this : — 



For a long time past sheep-skins, with very" long and stiffish 

 wool, furnislied by a cross between a lie goat and a ewe, have 

 formed a considerable article of commerce in Chili. The hybrid 

 is obtained thus : 



One he goat i"? put with ten ewes. 



The male hybrids have a wool very like horse-hair ; these 

 skins are not in high estimation where skins covered with hair 

 are wanted. 



But these male hybrids breed with ewes, and give a cross with 

 a fine soft horse-hair coat, which is in great demand — what are in 

 that country called Pellions, or Chabraques in French. 



After a few generations the hair becomes coarse and hard, 

 and then recourse must again be had to a male hybrid of the 

 first generation, for the purpose of getting a cross with hair of 

 the desired quality^ 



This fact, for which we are indebted to M, Gay, proves that 

 the male cross between a he goat and a ewe is not sterile. 



M. Flourens has obtained a cross between a Musimon and she 

 goat, but we do not know whether like the last it is productive 

 or not ; he has also obtained a sub-hybrid from a Musimon and 

 ewe. 



Again, M. de Lafresnais has presented to the Museum of Na- 

 tural History a pair of hybrids obtained from a male Guinea 

 Goose and a female Canada Goose, which belong to two entirely 

 distinct species ; and it is curious that their hybrids have already 

 bred as many as seven times. 



We will answer an objection that may be made to our defini- 

 tion of species, now that we have shown that there are hybrids 

 capable of breeding with certainty. 



Being without evidence as to whether a given individual re- 

 presents a species, we, like common people, defined the latter 

 from the greatest resemblance between individuals of the same 

 origin, or what is the same thing, from the transmission of the 

 same form through successive generations. When tiiis perpe- 

 tuity of form has once been established by experiment, by going 

 back as far as possible from the young to their progenitors, we 

 conclude that a species exists ; and we do not see, whatever may 

 be ultimately found to be the true definition of a species, why 



