VARIATION 43 1 



Some further remarks will be made about acquired characters 

 in the sequel. 



Neo-Lamarckism. — It is difficult to sum up in a few words 

 the beliefs of the Neo-Lamarckian school. They essentially 

 involve the view that there are general Laws of Growth, leading 

 to progress in definite directions, by means of successive varia- 

 tions of the same kind. The action of Natural Selection is largely 

 discounted. 



This chapter may perhaps best be concluded by the addition 

 of a few remarks on Variation and Heredity. 



VARIATION 



Beyond the fact that living matter does vary, we know very 

 little. No clear answer can as yet be given to the questions 

 why this should be so, and how variations of a given kind are 

 brought about. There can be no doubt, however, that the indi- 

 viduals of any particular species differ from one another in a great 

 variety of ways, and often to a very considerable amount. There 

 is, in fact, an illimitable field for the action of selected principles. 

 Many variations, too, are sudden or discontinuous, and probably 

 new species have been often evolved at a much more rapid rate 

 than supposed by Darwin, who believed in the selection and 

 accumulation of small variations. Since his time our knowledge 

 of variational possibilities has been largely increased. 



There can be no doubt that a large majority of the characters 

 of animals are adaptations to the environment, i.e. fit them to 

 live in relation to certain surroundings. The origin of such 

 adaptations must naturally be sought in variations. Here it is 

 necessary to clearly distinguish between variations of the soma 

 and variations of the germ, i.e. somatic and germinal variation. 

 As we have seen, the Lamarckians believe that the former 

 (acquired characters) can be transmitted. According to the 

 school of Weismann, on the other hand, it is only the germinal 

 variations which are capable of transmission. As, of course, the 

 development of a germ-cell into an individual means the pro- 

 duction of a new soma as well as more germ-cells, this new 

 soma will have been influenced by variations which have taken 

 place in the germ from which it has been developed. That is 

 to say, the character of a soma mainly depends upon the char- 



