

Ab 







ui^ol 



, ^ 



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> 1 



1 



IB 



^. intlf 



red •" 



f the la{« 

 grwttlf 



brwli;:!;: 



trpesfi 



"yund to ^ 



us. Soi 



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Fo. 



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f 8 I'-'- 





till 



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Ch. XXXVII.] 



LINN.EUS ON PEOTEAN GENEEA. 



323 



natural conditions of life. That clianges greater in degree or 

 even equal, but continuing uniformly in force for many thou- 

 sands of generations, should bring about the mutual sterility 

 of two allied races or species, is quite conceivable. 



If this point of divergence had been reached by the breeder 

 or horticulturist, the derivability of a new species by gradual 

 deviation from an old type would almost have ceased to be a 

 debateable question in natural history. 



Allusion has been made to the extinction of intermediate 



This would happen the more readily on the prin- 

 ciple well pointed out by Darwin, that in order that a given 

 area should support the greatest number of individuals, these 

 ought to belong to a great many widely dissimilar types ; and 

 what is true of genera, must sometimes be true of the races 

 of a species. There ' 



varieties. 



terms 



may 



place lor those of intermediate characters. 



Wild hybrid plants, and opinions o/Linnwus onprotean genera. 

 —If wild species were not averse to intermarry, or if their 

 hybrid offspring were not almost always sterile, it is obvious 

 that m a few generations there would be a blending too-ether 

 .of all existing types, and we should behold everywhere that 

 state of confusion which we now only meet with in certain 

 exceptional cases. 



To the occasional occurrence of protean or polymorphous 

 genera, as they have sometimes been called, where a -reat 

 number of closely alHed species occur, LinnEcus " 

 frequent allusion in his writino-s. 



makes 



He 



immu 



tability^ of primordially created species. In an address to 



he University of Upsala in 1751,- he gave a list of nearly 



thirty 'prolific' genera of nl.,Tif,« .'. ,.i.,-.t, .... . .^ 



were of doubtful oi 



genera of plants, in which the 



species 



wt J; , T™"' '^'' ''"''''''' ^"^ Sonth America, the 

 were so many mtermediate gradations between wl.at are 



* Ijinngeus, *Piantai HvIn-iVl^ ' oo i ta- 

 vol. iii. pp. 28-62. ' ' D'^scrtation of the Amo^nltatcs Acadoinic^, 



V 2 



