52 U. PERMANENCE OF SPECIES. 



which are now the names of aggregates. For instance, 

 what can back records do towards showing the distribu- 

 tion of the two very recent species before alluded to, 

 Arctium pubens and JRanunculusJioribundus ? Obviously, 

 nothing at all. While the invention of these book- 

 species must vitiate the back records for those older spe- 

 cies from which they have been carved ; that is, in the 

 ej'^es of all the botanists who adopt and believe in these 

 novelties. 



Under such circumstances, it is not surprising that 

 Phyto-geographers usually feel inimical to the practice of 

 hasty species-making on very slight grounds ; — that they 

 should so strongly object to the habit of pouncing upon 

 any trifling difl"erence between plants, and recklessly 

 assuming at once, without the trouble of test or trial, 

 that the plants thus slightly different will have also all 

 the theoretic characteristics of true natural species. 

 The Phyto-geogi'apher desires to know natural and dis- 

 tinguishable species as clearly and as numerously as he 

 can find them to be. But he wishes not to be himself 

 misled by false species, or to be impeded and perplexed 

 by the records of other botanists who are also misled by 

 them. 



5. Permanence of Species. 



The theoretic definition of the term Species (page 32) 

 was so worded as to include a repetition of the individu- 

 als, representatives of the species, during many genera- 

 tions. But it was not made a part of the signification of 

 the term, that the duration of a species should be per*- 

 petual. Geological records show that the species of 

 epochs long past were not the same as those of the pre- 

 sent time ; and consequently, so far as the future can be 



