THE LAMARCKIAN PRINCIPLE 49 



never been attacked. The comparative superiority, therefore, of 

 Europeans to the disease we are bound to attribute to the constant 

 elimination in past generations of those who were unable to resist it. 1 



There are other infectious diseases which come in a different 

 category and from among them we may select mumps as an 

 example. Mumps as a rule confers immunity on the sufferer, 

 but it hardly ever increases the death-rate and we cannot rank it 

 among ailments that eliminate. Accordingly mumps proceeds on 

 the even tenor of its way. It is what it always has been, a 

 nuisance but seldom more than a nuisance. Were Lamarckian 

 principles really operative among us, it would disappear or at 

 least, mild as it is, become still more mild, following the same 

 course as the eliminating diseases. 



If it is difficult to show how a modification can be transmitted The en- 

 from the body to the reproductive cells, it is no less difficult to * a n n ent 

 prove that the inherent character of any organ can be changed change the 

 by its environment. If children habitually go bare-foot, their Character 

 feet become hard, and this is, no doubt, a modification in the of an 

 accepted sense of the word. 2 They were born, however, with 

 feet whose nature it was to grow hard if unprotected, and all 

 that has happened, therefore, is that an existing characteristic 

 has been brought out. If gulls are fed on corn they will 

 develop something of a gizzard like the true gramnivorous 

 birds. 3 This may be explained by saying that they are born 

 with stomachs capable of becoming highly muscular should the 

 need arise. A green frog, if he is not among green leaves, but 

 amid dull colourless surroundings, ceases to be bright green 

 and becomes a sombre grey. Put him among foliage again and 

 his green soon returns. It cannot be said that the green foliage 

 has caused his colour to change. It is more correct to say that 

 he has the power of changing his colour to suit his environment. 



x See Nature, April 8, 1897. MM. Bourgatel and Brulfort found that tubercles 

 were invariably present in the lungs of Polynesians whose bodies were submitted to 

 post-mortem examinations. 



' 2 Modifications, the result of the action of the environment on the individual, 

 must be distinguished from variations, the inborn characters in which an individual 

 organism differs from its parents. 



3 See Lectures on Comp. Anatomy, by Sir Evarard Home, Vol. I., p. 271 ; and 

 Animal Economy, by John Hunter, p. 221. 



D 



