6 ON THE LAW WHICH HAS REGULATED 



the subject : 1st. The system of natural affinities. 

 2nd. The distribution of animals and plants in 

 space. 3rd. The same in time, including all the 

 phenomena of representative groups, and those 

 which Professor Forbes supposed to manifest polar- 

 ity. 4th. The phenomena of rudimentary organs. 

 We will briefly endeavour to show its bearing upon 

 each of these. 



The Form of a true system of Classification determined 

 by this Law. 



If the law above enunciated be true, it follows that 

 the natural series of affinities will also represent the 

 order in which the several species came into exist- 

 ence, each one having had for its immediate anti- 

 type a closely allied species existing at the time of 

 its origin. It is evidently possible that two or three 

 distinct species may have had a common antitype, 

 and that each of these may again have become the 

 antitypes from which other closely allied species were 

 created. The effect of this would be, that so long as 

 each species has had but one new species formed on 

 its model, the line of affinities will be simple, and 

 may be represented by placing the several species in 

 direct succession in a straight line. But if two or 

 more species have been independently formed on the 

 plan of a common antitype, then the series of affini- 

 ties will be compound, and can only be represented 

 by a forked or many branched line. Now, all at- 

 tempts at a Natural classification and arrangement 



