Invaporation. 469 



able number of species wbicb range from Middle and 

 Southern British Columbia to, more or less, the eastern con- 

 fines of Manitoba. 



Eocky Mountain Group. — Embracing the numerous 

 plants, not alpine, which in our present knowledge of 

 their range are confined to the valleys and foothills of the 

 Eocky Mountains. 



British Columbia Group. — Comprehending all those 

 species which are distributed somewhat generally over, and 

 are confined to, the Province of British Columbia 



Oregonian Group.— Including under this the more 

 southern plants found in British Columbia, and whose 

 range northward, from Oregon and Washington Territory, 

 has been facilitated by the general direction of the valleys 

 in the Eocky, Selkirk, and other mountain ranges there. 



Western Coast Group. — Including in this, not the shore 

 plants, but those species which probably the rain-fall and 

 other causes have confined to the neighbourhood of the 

 coast and the adjoining islands, in British Columbia. 



Sub-arctic Group. — Comprising species found on the 

 higher hills and mountains in Eastern Canada and British 

 Columbia, on Anticosti and the northerly coasts of the St. 

 Lawrence estuary, on the more exposed points of Lake 

 Superior and northward, and often intermingling far to the 

 northward with the true arctic species. 



Arctic Group. — Comprising a few rare representatives 

 in the Alpine districts of New England, and on the Mingan 

 Islands and Island of Anticosti and neighbouring coasts, 

 but as a rule confined to the high northern coasts of Labra- 

 dor and Hudson Bay, and to Greenland, the shores of Baffin's 

 Bay, the Arctic islands and Lower Mackenzie Eiver country. 

 {To be continued.) 



Invaporation. 



By W. L. Goodwin, D. So. 

 Professor of Chemistry and Mineralogy, Queen's University, Kingston. 



The experiments noticed in the Eecord of Science, Vol. 

 II., No. 4, Oct. 1885 (p. 259), have been continued since that 



