6o POPULAR SCIENCE MONTHLY. 



will never become established. Cases of this sort, in which a species 

 continually gives off mutations, that can not survive, and yet continue 

 to appear, are known. 



In most cases the survival of a species is not determined by one 

 particular character, but by the sum total of all. Therefore since the 

 characters mutate independently, we might expect to find occasionally 

 in a new species some characters more perfect than the actual require- 

 ments demand ; other characters less perfect than is necessary to main- 

 tain the species if survival depended on these alone, and many char- 

 acters that suffice for the demands of survival. Thus in man, to take 

 but a single example, the ear and the eye may be more perfectly de- 

 veloped in some respects than the demands of survival require, while 

 the appendix vermiformis is actually injurious to the welfare of the 

 race. The majority of the peculiarities lie somewhere between these 

 extremes. A new race of men can not be produced by selection of 

 those individuals that show fluctuating variations in these different 

 directions, but must arise by the sudden appearance of a new type or 

 types, which, finding a foothold, may establish themselves along side 

 of the present races.* It may be that definite variations are even at 

 present occurring, but are not of sufficient importance or difference to 

 attract attention. Permanent improvement must be looked for in this 

 direction, and not from the picking out of those individuals that 

 fluctuate in an advantageous direction. 



How Adaptation may arise through the Appearance of Definite 



Variations. 



If we take the position that the creation of new forms is not the 

 outcome of a long continued process of remodeling of each species, 

 but that new forms appear ' spontaneously,' how can we account for 

 the adaptation of new species to their environment? Are we to be- 

 lieve that all new forms that appear from ' inner causes ' will be already 

 adapted to some external set of conditions? A very slight familiarity 

 with living things will give, I believe, a negative answer to this ques- 

 tion. Nevertheless let us not conclude too quickly that none of the 

 new forms will be adapted to some environment, even if some of them 

 are not. 



Darwin defined natural selection as follows : ' This preservation of 

 favorable individual differences and variations, and the destruction of 

 those which are injurious, I have called natural selection, or the sur- 



*I do not, of course, mean to imply that any one of the present races of 

 mankind could not be greatly improved artificially by encouraging the indi- 

 viduals best suited to civilized conditions to propagate, and by disencouraging 

 propagation by the criminal, indolent and unhealthy individuals. Until this 

 is done we can not hope for even an artificial improvement in the standard of 

 the race. 



