How iSleed Modifies the Organism 305 



having a nervous system and the beginnings of conscious- 

 ness. In the former, vital activity depends upon the stimu- 

 lation received from without, so that the environment 

 produces direct effects. In the latter, on the contrary, there 

 is the initiation of suitable responses from within, so that 

 the environmental forces act indirectly. Lamarck also noted 

 the importace of the " balance " of nature and what came 

 later to be called the " struggle for existence " and the " sur- 

 vival of the fittest." In discussing the possible evolution of 

 man, he pointed out the bearing of isolation upon the es- 

 tablishment of distinct types, and the danger of an improved 

 form being swamped by the prevailing type. 



How Need Modifies the Organism 



The second law, which has resulted in a great deal of 

 ridicule and condemnation, is the expression of a philo- 

 sophical or metaphorical interpretation of the general fact 

 which we observe in living things under the name of re- 

 sponsiveness. Living things either adjust themselves to the 

 conditions of the moment — or they perish. It is hardly 

 fair to attribute to Lamarck, as did Charles Darwin in 1844, 

 the notion that change comes about through " the slow wil- 

 ling of animals." If we make allowance for the difficulty 

 of presenting simply and clearly in 1809 what came in the 

 course of a century to be accessible to schoolboys and school- 

 girls, we can the better understand Lamarck's point, whether 

 we agree with him or not. It seems reasonable, in view of 

 his w'hole work, to consider the doctrine of need or appe- 

 tency as equivalent to the assumption that the native tend- 

 ency of an animal is to respond to a change in the environ- 

 ment, or to a stimulus from outside, /// a mamter appropriate 

 to its own needs. How far is this tendency actually present? 

 How effective may it be in an unusual situation? How 

 profoundly will its exercise modify the organism? These 

 are entirely different questions. They are questions of fact 

 that must be determined by observation and experiment. 



