222 THE THEORIES OF EVOLUTION 



observed by Cunningham: "If, on the other hand, 

 we suppose the difference in colour of the two sides to 

 have been the result of a germ- variation, we need only 

 suppose that this was of such a kind that the colour 

 of the under side is only in a latent condition, and if an 

 external factor can cause a reaction to take place on 

 the light side, it is not surprising that this should call 

 forth the latent colour patterns. The result can be 

 given at least a formal explanation on the theory that 

 the original change was a germ-variation." 7 It is 

 very difficult however to conceive how a germ-varia- 

 tion, which is not controlled by the direct influence of 

 the environment, should have coincided precisely with 

 the absence of light, a factor which generally produces 

 discolouration, and how, furthermore, that accidental 

 variation could have affected the whole lot of fishes. 

 Why seek such a complex explanation when the facts 

 suggest naturally a much simpler one? 



One of the best examples of transmission of an 

 acquired character is supplied by A. Hyatt, one of the 

 foremost exponents of Neo-Lamarckism, who has 

 made a special study of certain cephalopods of which 

 only one species, the Nautilus, has survived. 



Since their first appearance in primary strata, the 

 shells have successively assumed many different 

 shapes: the straight beehive shape (orthoceran shells), 

 then a curved shape (cyrtoceran) , which becomes more 



7 Evolution and Adaptation, p. 259. 



