The TOUHO HATOEAIIST* 



A Penny Weekly Magazine of Natural History. 



No. 112. DECEMBER 31st, 1881. Vol. 8. 



DARWINISM. 



Second Paper. 



IT was pointed out in our last paper 

 that the tendency of varieties pro- 

 duced in a state of nature to disappear, 

 and of those produced during domesti- 

 cation to revert to the original type when 

 they were allowed to run wild, had been 

 considered a strong reason for supposing 

 that species were really permanent. We 

 will consider first whether the proposi- 

 tion that varieties produced in a state of 

 nature have a tendency to disappear be 

 really true. Mr. Darwin calls his book 

 ** The origin of species by means of 

 natural selection, or the preservation of 

 favoured races in the struggle for life." 

 Its argument is to the effect that 

 whenever a change is produced that is 

 an advantage to its possessor, there will 

 be a tendency to transmit that form to 

 successive generations. Take the case 

 of a race of animals such as antelopes, 

 that are preyed on by the carnivorous 

 mammalia inhabiting the same regions. 

 If a herd of antelopes be pursued, the 

 swiftest will certainly escape, the slow- 

 est fall victims to the enemy. The 

 survivers of the herd are so by "Natural 

 Selection." They were fitted to escape 

 by speed, and those possessing that 



quality to the highest degree did escape. 

 It is evident that the progeny of these 

 swiftest animals are more likely to be 

 swift than would have been the progeny 

 of the slower members of the herd. 

 The tendency, therefore, will be to 

 transmit the quality in excess, because 

 the slower members have been weeded 

 out, and only tlie swifter remain to 

 perpetuate their race. In another gen- 

 eration the same thing will again obtain. 

 The members of the herd will still vary 

 in speed and power of endurance ; again 

 the slower will be captured and devour- 

 ed, and again the swifter will remain to 

 hand down their improved qualities to 

 yet another generation. In the course 

 of time — ages it may be — these succes- 

 sive changes will have produced a per- 

 ceptible difference. It may be that 

 extra length of leg gave the extra speed, 

 in which case we may expect to find 

 that this "Natural Selection" all in 

 one direction for a great length of time 

 has reo.lly produced a race of animals 

 with longer legs. But while this has 

 been going on, let us suppose a variety 

 to have been produced, which, from its 

 colour being more in harmony with the 

 hue of the surrounding objects, was less 

 likely to be observed from a little dis- 



