ORIGIN OF PLANTS. 223 



the future, — we find no repetition of species. If the produc- 

 tion of perfect duplicates or triplicates in independent cen- 

 tres were a law of nature, our works of physical science could 

 scarce fail to tell us of identical species found occurring in 

 widely-separated systems, — Scotch firs and larches, for in- 

 stance, among the lignites of the Lias, or Cyprina islandica 

 and Ostrea edulis among the shells of the Mountain Lime- 

 stone. But never yet has the geologist found in his systems 

 or formations any such evidence as facts such as these might 

 be legitimately held to furnish, of the independent de novo 

 production of individual members of any single species. On 

 the contrary, the evidence lies so entirely the other way, 

 that he reasons on the existence of a family relation obtain- 

 ing between all the members of each species, as one of his 

 best established principles. If members of the same species 

 may exist through de novo production, without hereditary re- 

 lationship, so thoroughly, in consequence, does the fabric of 

 geological reasoning fall to the ground, that we find ourselves 

 incapacitated from regarding even the bed of common cockle 

 or mussel shells, which we find lying a few feet from the sur- 

 face on our raised beaches, as of the existing creation at all. 

 Nay, even the human remains of our moors may have be- 

 longed, if our principle of relationship in each species be not 

 a true one, to some former creation, cut ofi* from that to which 

 we ourselves belong by a wide period of death. All pal8e<m- 

 tological reasoning is at an end for ever, if identical species can 

 originate in independent centres, widely separated from each 

 other by periods of time ; and if they fail to originate in pe- 

 riods separated by time, how or why in centres separated by 

 space 1 



Let the reader remark further, the bearing of those facts 

 from which this principle of geological reasoning has been 

 derived, on the development hypothesis. We find species re- 

 stricted to circles and periods ; and though stragglers are oc- 



