80 PHYSICAL INVESTIGATION. [PART I. 



we have learned to regard as the results of different degrees 

 of mental culture, warn us not to under-estimate the latter. In 

 confining ourselves here to the physical changes to which man 

 is exposed, in order to show the exaggeration of the influence 

 of climate and soil upon psychical life, we must first consider 

 that a perfect dependence of man upon surrounding nature only 

 occurs when he is in a primitive state ; no sooner does he rise 

 to a higher state of culture, than he ceases entirely to corre- 

 spond to the natural conditions. There is another important 

 circumstance which must be borne in mind, that no people can 

 exactly in its external aspect correspond with surrounding 

 nature, inasmuch as, probably without exception, all peoples 

 have only arrived at their present localities after more or less 

 extensive migrations. Hence, it is explicable how, from the 

 various crossings and differences of direction which the peoples 

 have taken in their migrations, we should find nations of such 

 various types under the same degrees of latitude and under 

 similar climatic conditions ; for in consequence of these migra- 

 tions, there must have been for them an accumulation of climatic 

 influences, as Latham calls it. 1 By successively settling in 

 different latitudes, they have for a shorter or longer time ex- 

 perienced various external influences, and have passed through 

 different modes of life and degrees of culture. 



Besides climate, physical and mental culture, there is another 

 source whence arise the changes to which the organism is 

 subject in the course of many generations : namely, the spon\ 

 taneous origin of new peculiarities. This can only be reduced 

 to a predisposition in certain individuals to deviate from the 

 physical form of their parents without our being able to 

 explain the how and the why these deviations occur, and whence 

 they arise in those who first exhibit them. It is for this reason 

 that we term such peculiarities spontaneous, and consider them 

 specially, although it can scarcely be doubted that they are 

 owing to the same causes which have occupied our attention 

 hitherto. 



1 Latham, " Nat. Hist, of the varieties of man." 



