MAN. 35 1 



issoclatloii of mucous granules constitutes a definitely-formed 

 cytoblast, around which a vesicular membrane fornis a closed 

 cell," this cell being either produced from another pre-existing 

 cell,* or being due to a cellular formation, which, as in the 

 case of the fermentation-fungus, is concealed in the obscurity 

 of some unknown chemical process.! But in a work like the 

 present we can venture on no more than an allusion to the 

 mysteries that involve the question of modes of origin ; the 

 geography of animal and vegetable organisms must limit itself 

 to the consideration of germs already developed, of their hab- 

 itation and transplantation, either by voluntary or involuntary 

 mio-rations, their numerical relation, and their distribution 

 over the surface of the earth. 



The general picture of nature which I have endeavored to 

 delineate would be incomplete if I did not venture to trace a 

 few of the most marked features of the human race, considered 

 with reference to physical gradations — to the geographical 

 distribution of cotemporaneous types — to the influence exer- 

 cised upon man by the forces of nature, and the reciprocal, 

 although weaker action which he in his turn exercises on 

 these natural forces. Dependent, although in a lesser degree 

 than plants and animals, on the soil, and on the meteorolog- 

 ical processes of the atmosphere with which he is surrounded 

 — escaping more readily from the control of natural forces, by 

 activity of mind and the advance of intellectual cultivation, 

 no less than by his wonderful capacity of adapting himself to 

 all chmates — man every where becomes m.ost essentially asso- 

 ciated with terrestrial life. It is by these relations that the 

 obscure and much-contested problem of the possibility of one 

 common descent enters into the sphere embraced by a general 

 physical cosmography. The investigation of this problem will 

 impart a nobler, and, if I may so express myself, more purely 

 human interest to the closing pages of this section of my work. 



The vast domain of language, in whose varied structure we 

 see mysteriously reflected the destinies of nations, is most inti- 

 mately associated with the affinity of races ; and what even 

 slight differences of races may effect is strikingly manifested 

 in the history of the Hellenic nations in the zenith of their 

 intellectual cultivation. The most important questions of the 

 civihzation of mankind are connected with the ideas of races, 



* Schleiden, Grundzuge der icissenechaftlichen Botanik, 1842, th. i., 



B. 192-197. 



t [On cellular formation, see Heufrey's Outlines of SlrnciuiaJ and 

 Physiological Botany, op. cit., p. lG-22.]— S^V. • 



