ConsideralioHi comiecfed relth the Glacier Theory. 49 



tain limestone systems were different from one another, I 

 said, not only to my pupils, but in various published papers,* 

 that these naturalists would the less deny a mixture of the 

 fossils of the different systems the more they extended their 

 views beyond the small country of England, and looked about 

 them over a greater surface. 



The result which has been obtained, that the species by 

 no means became extinct at the end of each period, but 

 partly lived during the succeeding one, also proves that these 

 periods cannot have been separated in a very marked way ; 

 that such periods, to assume which has been so convenient for 

 us, and will probably remain so for some time longer, have 

 never existed universally over the whole surface of the earth ; 

 hence that a sudden refrigeration after a uniformly warm con- 

 dition of the earth could not have destroyed simultaneously all 

 life, in order to make way for a new race of beings, as is sup- 

 posed by the ice-hypothesis, and that this universal cooling 

 which is asserted, it is not known where or how, to have been 

 brought upon the earth from time to time, also never existed. 

 But against this " geological" view there now makes its ap- 

 pearance a new opponent that 1 have not yet mentioned, one 

 which is intimately connected with the ice-h;^othesis, and is 

 the most alarming of all, viz. the hypothesis,t " that no cha- 

 racter, that is, no distinguishing mark (of an organism) ought 

 ever to be regarded as so trifling as to point to absolute iden- 

 tity ; that it is not characters which mark out the species, but 

 the combined relations to the external world in all the cir- 

 cumstances of life,'' (which, however, in fossil beings, are re- 

 duced solely to their stratographical distribution and their 

 association with other species !). *' Therefore the species can- 

 not be recognized by resemblances, but only by their rela- 

 tions ;" and without doubt, " in futm'e it will be necessary to 

 express the specific difference of organic remains by the cir- 

 cumstances of their occurrence, without it being possible to 

 assign distinctions to them. And instead of being involved 

 in boundless uncertainty, our science will emerge from its 

 dry foundation to a state of rich blossom," that is, provided 



* Jahrhv.ch, 1839, p. 736, note; 1841, p. 97 ; 1841, p. 817, &c. 

 t Jameson's Journal, vol. xxxii. p. 97. 



VOL. XXXIIt. NO. T.XV. JVLY 1842. J> 



