288 Prof, Guthrie^ LL.B. — On the Subjective Causes of [April 25^ 



Thus on page 319 we read : 



" There is no evidence, as was remarked in the last chapter, of 

 the existence of any law of necessary development." 

 And on page 291 : 



" These several facts accord well with our theory which includes 

 no fixed law of development, causing all the inhabitants of 

 an area to change abruptly or simultaneously, or to an 

 equal degree." 



If, however, these passages be carefully read with the context it 

 will appear that the law of development here denied is not one 

 affecting the individuals of particular species only but the individuals 

 of all species inhabiting a given area. 



Nevertheless the following passage seems to shew that at the 

 time of the publication of the first and earlier editions Darwin believed 

 that species did originate from the casual variation of an individual^ 

 and that it was only after the year 1867 that he came to the 

 conclusion that new permanent varieties and consequently new 

 species could only be formed by similar and simultaneous variation: 

 in many individuals of the same species. 



In the IVth Chaptsr of the 6th edition, page 71, after illustrating 

 the action of natural selection by the example of the swiftest and 

 slimmest wolves alone being able under certain circumstances to • 

 subsist and propagate their race, he goes oa to say : 



" It should be observed that in the above illustration I speak 

 of the slimmest individual wolves, and not of any single 

 strongly marked variation being preserved. In former 

 editions of this work I sometimes spoke as if the latter 

 alternative had frequently occurred " . . . " until reading 

 an able and valuable article in the North British Review 1867 

 I did not appreciate how rarely single variations whether 

 slight or strongly marked could be perpetuated" .... 

 " It should not .... be overlooked that certain rather strongly 

 marked variations, which no one would rank as mere 

 individual differences, frequently occur owing to a similar • 

 organization being similarly acted on." .... 

 " There can be little doubt but that the tendency to vary in the 

 same manner has often been so strong that all the i?idividualsr 

 of the same species have been similaidy modified without the^ 

 aid of any form of selection. '''' 



