i88 NATURAL SCIENCE. March. 



war. If the one force predominate we have evolution, if the other, 

 retrogression ; if the two forces balance one another, the species in 

 which this occurs undergoes for a time neither evolution, nor retrogres- 

 sion." To speak of natural selection as a cause of progression, is 

 certainly a debatable point ; but atavism cannot be called a cause of 

 retrogression. It is a phenomenon of retrogression ; and it is certainly 

 not a force. Atavism, indeed, is a much misunderstood term. Some 

 writers have called the features of the normal infantile stages of onto- 

 geny, such as monkey-habits of a child, atavic ; which is clearly incor- 

 rect. Mr. Reid describes atavism as " a failure to recapitulate in the 

 ontogeny the last stages of phylogeny — it is an arrest of development." 

 (p. 47.) He thinks that he is in agreement with Herbert Spencer, who, 

 however, defines it as a recurrence of ancestral traits. But particular 

 facial features appearing in an individual, after having missed several 

 generations, need not necessarily be arrest of development. That 

 would leave a man of our race with a negroid type of nose, such as is 

 common to all young children. It requires a more extended develop- 

 ment than obtained in the immediate ancestors to reproduce that 

 highly specialised type of nose, which attracts attention as a character- 

 istic of certain families. Again, another phenomenon often called 

 atavic is the return to ancestral features exhibited in senility, for 

 instance, loss of teeth in man and increasing tendency to a hairy body. 

 For such phenomena there has been proposed the term hypostrophy, 

 which is a truer rendering of the facts as gathered from palaeontology. 



Rightly enough, Mr. Reid insists that natural and artificial 

 selection are but terms for different exhibitions of one phenomenon, 

 and that man himself is as subject to the laws of evolution as is any 

 other organism. There are naturalists, who so far belie their name, 

 that as soon as they consider man, and what man does, they assume 

 super-natural agencies. Mr. Reid does not make this mistake. Man, 

 indeed, is a most potent influence in modifying the environment of all 

 species, his own included ; but though alteration of the environment 

 changes the manner of evolution, it does not stay its action. Man's 

 reason has caused him to cultivate, and so give special forms to, certain 

 species ; but in the main his reason has made him the most formidable 

 beast of prey that has ever appeared on. the earth. Other animals 

 have taken life to sustain their own. Man does more : he takes it 

 ruthlessly for the gratification of his vanity, for the mere sake of 

 destruction, or from religious zeal. Man's reason has profoundly altered 

 the conditions of environment the world over ; and it has been the 

 cause of the greatest misery to the organic world, himself included. 



To turn to the first part of Mr. Reid's work, dealing with organic 

 evolution. This is discussed on the assumption of the non-inheritance 

 of acquired characters. "Biologists generally," says the author, 

 "are gradually veering round to this opinion." This may be doubted. 

 Certainly palaeontologists favour the Lamarckian teaching, modified 

 by a doctrine of the appearance of characters gradually earlier in each 



