EXPLANATIONS OF THE FORMULA. 67 



too many. In looking down the series, it will be observed, 

 that the gi'oups of species, so indicated, pass into each 

 other. Thus, the pratal plants are occasionally pascual 

 plants, as Phleum pratense ; the pascuals ai"e in tui'n erice- 

 tals, as Prunella vulgaris ; the ericetals pass into uliginals, 

 as Scii-pus caespitosus, and so on. 



The remainder of the paragraph, continued from the 

 tenth line, is devoted to any remarks in explanation of the 

 epitome, or such other observations as may appear requi- 

 site ; due regard being had to restriction in the quantity of 

 text. A great and interesting division of the general sub- 

 ject is left untouched here ; namely, the relations of plants 

 to the soil and subjacent rocks, hitherto neglected, or only 

 attempted in a feeble and inadequate manner. Inquuies 

 in relation thereto would demand a different method of 

 treating distribution, scarcely compatible with the wider 

 and more comprehensive objects here aimed at. This work 

 deals with the climatal and geogi'aphical relations of plants : 

 there is still room and call for another, devoted to their 

 geological and mineralogical connexions ; for such con- 

 nexions they undoubtedly have in an intimate degree. 



But " non onmia possumus onmes " is a maxim which 

 must needs be acknowledged by liim who seeks to caiTy 

 forward any department of science. He may take a wide 

 field, who wishes only to learn over again what others have 

 first ascertained and recorded ; but he must keep to a nai'- 

 rower track, who attempts to step beyond the knowai and 

 familiar gromid. And, at best, he will move slowly when 

 once beyond the beaten road. 



After all the time and thought devoted to preparing the 

 materials for the present work, in compihng fi-om the writ- 

 mgs of other botanists, in sifting out the false fi-om the 

 true, and in collecting avast number of additional facts and 

 notes in the wUds of nature, the Author may well fear that 



