325 



in the long-established sense of this word, but rather 

 "cross-breeding." The two processes are, however, fun- 

 damentally the same, and their results are sufficiently 

 distinguished by the terms Species-hybrid, or Genus- 

 hybrid, and Variety-hybrid. We are thus led to brief 

 notice of the meaning of the terms Species and Vari- 

 ety, and of the distinctions employed in Botanical 

 Classification. 



Species. Until recently naturalists generally held 

 the view that in " the beginning" certain kinds of plants 

 and animals were separately created, with the power to 

 reproduce their own kind, but incapable of fertile hybrid- 

 ization, so that only such original kinds could be per- 

 petuated. Such supposed original kinds were called 

 Species. At present, on the contrary, most biologists 

 regard all existing kinds of plants and animals as prob- 

 ably the results of a very slow and gradual development 

 or evolution from one vastly remote ancestor of the sim- 

 plest type. On this view a Plant-Species comprises a 

 number of individuals, "among which we are unable to 

 distinguish greater differences than experience shows us 

 we should find among a number of plants raised from 

 the seed of the same parent." 



On the former view, plants yielding fertile hybrids or 

 crosses must be Varieties of the same species. On the 

 latter view different Species may hybridize. They are 

 not originally different, and by Evolution or Reversion 

 may pass into each other. On either view, the distinc- 

 tion of plants into species is practically the same, being 

 largely a matter of expert judgment or agreement among 

 authorities, and not capable of exact decision by refer- 

 ence to fixed rules or known natural laws. The charac- 

 ters that are taken to be common to all the individuals 

 of a species are termed specific characters. The differ- 

 ences used to divide plants into species are called specific 

 differences. 



