344 QUESTIONS TO BE ANSWERED. 



But do the plants themselves follow, from the equator to 

 the poles, the same law of decrease as obtains from the base 

 to the summit of the loftiest equatorial mountains ? 



Under identical isothermal lines, is the ratio of families 

 known and identified to the probable aggregate of Phanero- 

 gams the same, in the temperate zone, on either side of the 

 equator ? 



What are the vegetable families which preponderate at the 

 two extremes, represented by the torrid and the frigid zones ? 



Under the same geographical latitude, or between the 

 same isothermal lines, are the Synantherae, the Gramineae, the 

 Leguminosae, the Labiatae, the Cruciferse, the Umbelliferse, 

 more numerous in the Old than in the New World ? 



What families, either through their mass of individuals or 

 their number of species, take precedence of the other Phanero- 

 gams? 



How many species of one and the same family belong to 

 any particular country ? 



What groups or families are characteristic of each zone ? 



Is the present classification of genera and species in all 

 respects what could be desired ? 



These are questions that require to be considered, and to 

 some of them we shall presently attempt replies. 



Herbariums, though their classification is too frequently 

 imperfect, may furnish us with data of great utility. The 

 great herbarium of Benjamin Delessert was estimated, after 

 his death, to contain 86,000 species, a total not widely 



