THE UNITY OF THE HUMAN SPECIES. 71 



When, on the contrary, individuals which are only of different 

 races, hut of the same species, are Drought together, that is to say, 

 when we produce a mongrel, is the result the same ? No, it is exactly 

 contrary. 



These crossings are always fertile, and sometimes more so than the 

 union of animals of the same race. But especially the children and 

 grandchildren are also as fertile as the parents and grandparents ; so 

 much so that they propagate their kind indefinitely. The difficulty 

 here is not to procure mixed races y the difficulty is, when we have 

 pure races that we desire to preserve, to keep strange blood from modi- 

 fying them. 



Races thrive by crossing that is, by the union of different races 

 of the same species, they multiply abundantly around us ; such are our 

 street-dogs, our roof-cats, our coach-horses, all our animals where the 

 race is indistinct ; because of cross-breeding in all directions, the differ- 

 ential characters becoming confounded. 



So far from experiencing difficulty in obtaining offspring from races, 

 the men who are occupied with cattle, with sheep, with horses, ama- 

 teurs in dogs, in pigeons, know with what watchful care they must 

 protect their favorite race. 



Here, then, is a general fact, and from this fact it results that 

 fertility is the law of union between animals belonging to different 

 races (Mixed Beeeding). 



Here, gentlemen, you see the great distinction, the fundamental 

 distinction, between species and race. And, it is all the more important 

 to recognize and record this distinction, as it facilitates experiment. 

 When you have two different vegetables, or two different animals, 

 and wish to know whether they belong to two distinct species, or only 

 to two races of the same species, marry them. If the union proves im- 

 mediately fertile, if the fertility is propagated and persists, you may 

 affirm that, notwithstanding the differences which separate them, these 

 vegetables and these animals are only races of the same species. If, 

 on the contrary, you see the fertility disappear completely or diminish 

 notably at the first union, if you see it decreasing, and go on diminish- 

 ing, to disappear at the end of a few generations, you may without 

 hesitation affirm that these vegetables and these animals belong to 

 distinct species. 



Gentlemen, I have discoursed at length of vegetables and animals, 

 of the coffee-tree, of the turkey, of the rabbit, of the dog, of the cat, 

 of cattle, etc., and you may think that I am forgetting man. On the 

 contrary, I have not ceased to think of him. 



What is our question concerning man ? Distinctly this. 



Look once more at these designs. They show you differences, 

 marked enough, between the human groups, although less considerable 

 than at first appears. 



Now, we do not know the type or the primitive types of these 

 human groups. 



