270 



TIIEOEIES AS TO THE NATUEE OE SPECIES. [Ch. XXXV 



at a recent period into tlie territories where we now find 

 them. It is difficult to look forward to the time when we 



m 



number 



all the marine tribes, and to by far the 



the terrestrial ; — such as birds, and insects, and a large pro- 



portion of plants, especially those of the cryptogamous class, 



many 



almost cosm 



ma}' 



called into being by special acts of creation, some forest tree 

 or new quadruped ought to have been seen, for the first time, 

 within the last ten or twenty centuries in the more populous 

 parts of such, countries as England or France. In that 



case 



the naturalist might have been able to demonstrate 



that no similar living form had before existed in the district. 

 Now, although this argument may seem plausible, its force 

 will be found to depend entirely on the rate of fluctuation 

 v/hich we suppose to prevail in the animate world, and on 

 the proportion which such conspicuous subjects of the animal 

 and vegetable kingdoms bear to those which are less Imown 

 and escape our notice. There are perhaps more than a 

 million species of plants and animals, exclusive of the mi- 

 croscopic and infusory animalcules, now inhabiting the ter- 

 raqueous globe. The terrestrial plants may amount, said 

 De CandoUe in 1820, to somewhere between 110,000 and 

 120,000.^- Mr. Lindley, in a letter to the author in 1836, 

 expressed his opinion that it would be rash to speculate on 

 the existence of more than 80,000 phsenogamous, and 10,000 

 cryptogamous plants. ' If we take,' he says, ' 37,000 as the 

 number of published phsenogamous species, and then add. 



ISTew Holland 



10,000 in Africa, and 18,000 in Amer 



we have 80,000 



species ; and if 7,000 be the number of published cryptogamous 

 plants, and we allow 3,000 for the undiscovered species (mak- 

 ing 10,000), there would then be, on the whole, 90,000 species.' 



Hooker 



limits 



* Geog. cles Plantes. Diet, des Sci. Xat. 



4 



I 



W 



P 



IC'l 



150.0' 



iiis 



may J ' 



Great 



that i 



ordii] 

 The 



c 



exceec 

 1,200 



mated 

 forms 



were J 

 that a 

 thevi 



tohai 

 io ad 

 sive 



It 

 what ' 



of the 



can h 



tinenti 

 area is 



life^t" 



] 



