14 rUELIMINARY INQUIIUES. 



To my multiple origin, comiminication and direct derivation is essential. The species is com- 

 pounded of many influences brought together through many individuals, and distilled by Nature into 

 one species ; and, being once established, it may roam and sjDread wherever it finds the conditions 

 of life not materially different from those of its original centre. 



I may add that I do not imagine that time has anything to do with the change or creation 

 of species, fui-ther than as it gives greater opjoortunity for the occurrence of change. Species may 

 vibrate backwards and forwards between two differently situated districts in the same country, and 

 at each vibration give off new forms, while the portion of the old which have not moved still sub- 

 sist, and the longer time there is for this to go on of course the greater nimiber of sjiecies will the 

 country contain. It is thus not solely because Africa is a tropical, and in many parts a productive 

 land, that the number of its sj)ecies is great, nor is the paucity of species in Siberia wholly due 

 to the ungenial nature of its soil and climate. The one owes its prei^onderance over the other also 

 partly to the comparatively long period which has elapsed since it became dry land, and the other 

 its deficiency partly to the short time which has elapsed since it emerged from below the waters. 



For practical purposes, however, my opinion regarding the origin of species merely requires 

 the coincident pre-existence in time and place of some other species from which it may have been 

 derived ; it may have been derived, as I siippose, through the effect of change letting loose an 

 innate power of variation, or, as Mr. Darwin supposes, by selection. It may have been by descent 

 from one individual in whom the change has been effected, or, as I now believe, by the impress of 

 change being extended over all the individuals similarly situated. I am not greatly concerned to 

 explain the exact mode of operation of the laws evolving new species. What I cannot do 

 without, however, is the assumption that there is some law having such effect, and that de- 

 scent is the only possible explanation of relationshijj and distribution. 



