62 GENESIS OF MAN. 



But perhaps the most surprising part of this whole course is its 

 one great stride through the entire mammalian class, from the 

 marsupial to the lemur. All vain expectations of finding some 

 thread of relationship that should lead through the labyrinth of 

 varied mammalian orders, and connect us with the horse, the dog, 

 the elephant, etc., are thus happily set at rest, and we are permitted 

 only to claim such consanguineal relationship with the opossum, 

 the lemur and the ape. 



In fact, instead of a long concatenated "chaine animate," as La- 

 marck supposes, the animal kingdom presents rather a tree, spread- 

 ing from very near the base with almost a whorl of unequal 

 branches or subordinate trunks, each of which is again variously 

 branched, giving the whole the form of an inverted cone or pyra- 

 mid. At the upper extremity of each of these branches, which 

 have come a long way independently of each other, is found one 

 of the great groups or types of now living creatures, man occupy- 

 ing the highest summit of the vertebrate branch. 



Contemplating now the great number of branches that arise at 

 different points, some of which are short and apparently stunted, 

 while others push upward with different degrees of vigor, only 

 one or two reaching truly lofty and commanding positions, the 

 thought forcibly strikes us that this picture reveals the universal 

 tendency of Nature to develop organic forms. We realize that 

 this vital force or nisus is constantly pressing at every point, but 

 that as the conditions of life are limited, success is possible only at 

 a few points ; that in consequence of obstacles of many kinds, not 

 the least of which are offered by organic conditions themselves 

 that have pre-occupied the field, the degree of success at these 

 points varies widely, and produces all grades of vigor, size, length, 

 and ramification among the branches. The highest and most 

 thrifty branches mark the line of absolutely least resistance; the 

 shorter and less vigorous ones indicate lines offering varied degrees 

 of resistance; while the stunted, dwarfed, and retrograde branches 

 show lines of resistance so great that the vital force barely over- 

 comes it. Finally, all points from which no buds or branches 

 arise teach us over how large a proportion of nature the resisting 

 agencies wholly overbalance the organic tendencies, and no life 

 can originate. 



Another thought to which the attentive contemplation of this 



