iv.] OF THE ANCIENTS. 141 



Deodaras did not suffer. Does not this fact sug- 

 gest some unexplained condition of climate which, 

 operating upon the species over a long lapse of 

 years, has at length reduced it to the narrow limits 

 in which it is found native unless indeed we fall 

 back upon that higher law, which prescribes to 

 each species a limited period of duration, and sup- 

 poses this period to be arriving in the case of this 

 remarkable vegetable production ? 



It may be said, indeed, that such an inference is 

 contradicted by the vigorous growth and gigantic 

 proportions which this tree assumes in the spots 

 where it still exists. Yet the same remark would 

 apply to several other trees of great size and vigour, 

 such as the Dracaena draco, the Callitris quadri- 

 valvis, and the Glyptostrobus heterophyllus 7 -, now 

 confined to one country, though formerly of much 

 more extensive distribution. 



In these cases, also, it is difficult to point out 

 what changes of climate could have led to their 

 being thus restricted within their present range. 



But it is time to bring these Lectures to a ter- 

 mination, in concluding which I cannot help re- 

 marking upon the small progress made in natural 

 knowledge between the period of Alexander and 

 Trajan, a distance of time amounting to not less 



1 Callitris, found now in Algeria, has been detected in the Miocene 

 formation of Aix, in Provence. (Count Saporta in the Ann. des So. 

 Nat.) Glyptostrobus, found now in China and Japan, had spread during 

 the tertiary period over Switzerland ; Dracaena draco is now confined 

 to Teneriffe. 



