XX TRANS LA TOR 'S PRE FA CE 



ent of conditions ; the fact that " acquired " characters 

 disappear when the conditions to which they are due are 

 removed is no more evidence against the inheritance of 

 such characters than the fact that the oricjinal characters 

 disappear under the new conditions is evidence against the 

 heredity of those original characters. We know nothing 

 more about heredity than that it is a name which we give 

 to the generalisation that organisms remain constant in their 

 characters within narrow limits of variation so long as the 

 conditions of life remain unchanged, and retain their char- 

 acters for a time after those conditions are changed. 



Whether it can be proved that adaptations are due to 

 the inheritance of acquired characters or not, it is at least 

 certain that the Lamarckian view explains the evolution of 

 adaptations as perfectly as Weismann's theory. Nay, more 

 perfectly, for the theory of selection can never get over the 

 difficulty of the origin of entirely new characters. It may 

 be said that the necks of the giraffe's ancestors were of 

 different lengths, and the selection of the longest produced 

 the striking? length of neck we now see. But how can it 

 be said that the horns of ruminants arose ? No other 

 mammals have ever been stated to possess two little 

 symmetrical excrescences on their frontal bones as an 

 occasional variation ; what then caused such excrescences 

 to appear in the ancestors of horned ruminants ? Butting 

 with the forehead would produce them, and no other cause 

 can be suggested which would. 



There is evidence that physiological change precedes 

 morphological. There is a climbing kangaroo in Papua 

 which shows so little adaptation of structure to the climbing 

 habit, that no naturalist would believe from the mere study 



