114 EXPLANATIONS. 



kingdom,] actually differing less from each other 

 than the known varieties of certain variable 

 species, which a Lamarkian might suppose to be 

 of so recent an origin, as not to have yet become 

 settled in the possession of their proper diagnostic 

 characters. Indeed, notwithstanding the assump- 

 tion to the contrary, by authors who have little 

 practical acquaintance with the details of natural 

 history, the proper discrimination between species 

 and variety, is one of the greatest difficulties 

 which the naturalist has to encounter ; and he 

 who is successful in tliis department is entitled to 

 a rank which comparatively few can attain."* 



Of the extent to which modifications may be 

 carried by palpable external conditions, I may 

 now supply a few illustrations. It is well known 

 that fungi and lichens attain to very different 

 appearances in different situations, in conformity 

 with different conditions. Fries, we are told, 

 " asserts that out of the different states of one 

 species (telephora sulphm^ea,) more than eight 

 distinct genera had been constructed by different 

 authors. It would seem, then, that the absolute 

 number of species among the fungi is not nearly 

 so great as has been usually supposed ; and that 



* Boston Journal ot Natural History. 



