THE EVOLUTION OF LIVING BEINGS. 49 



their tatoo-marks. If the different species have not 

 intercrossed, we will find that, although the armies we 

 now compose, consist of different individuals than 25 

 years ago, they yet have the same constitution as for- 

 merly, although it may not be possible to place all the 

 children in the regiments of their parents, because their 

 tatoo-marks may show that a woman from one regi- 

 ment has married a man from another regiment, 

 be it of the same species as she-herself. This howe- 

 ver does not affect the species, so that nature in this 

 case has kept our species pure, our species thus coin- 

 ciding with those of nature. 



Suppose on the other hand that crossing has occu- 

 red, but has been limited to the individuals belonging 

 to the same regiments of the second army. Then the 

 tatoo-marks will show this to us, and so we will be 

 able to put the children though many of them will 

 be crossbred, others of course may be pure because 

 their parents belonged to the same species into the 

 same regiments to which their parents belonged. 



Nature therefore has made the same groupings as 

 we did, her regiments coincide with ours, her Linneons 

 with ours, although each of them contains hybrids 

 which ours did not. 



But suppose crossing had been promiscuous be- 

 ween all the species in the second army, then we would 

 be unable to assign to the new recruits places in the 

 same regiments in which their parents had served, be- 

 cause many of them would carry tatoo-marks of diffe- 

 rent regiments. 



In that case therefore, nature had not made grou- 



