The Essence of Lamarcl^s Teaching 307 



happens in such a case? The pathologist may be content 

 to tell us that the tissues of the body, or perhaps certain cells 

 only, elaborate an antitoxin, a something that counteracts 

 or neutralizes the poison of the diphtheria bacillus. How is 

 this result brought about? Does the organism's *' need " 

 automatically guide the physico-chemical reactions of the 

 white blood cells? Is there perhaps an " instinct " for re- 

 sponding appropriately to such a stimulus? We have al- 

 ready intimated that, waiving the assumption that the 

 giraffe's stretching will actually lengthen his neck, we have 

 still to find out how the animal comes to stretch at all. The 

 primary disposition to respond appropriately to the situation 

 is after all an inseparable part of our conception of living 

 things. We may therefore grant Lamarck's premises, even 

 if we reject his conclusions, pending further information 

 regarding the source and the mechanism of this primary 

 responsiveness. 



It is not necessary to assign to Lamarck's second law an 

 anthropomorphic intent; and Lamarck himself recognized 

 that the formulation does not apply to plants and to many 

 animals, although the distinction may not be due, as he 

 supposed, to the presence or absence of a nervous system. 



The Essence of Lamarck's Teaching 



The center of controversy in Lamarck's doctrine is 

 found in his fourth law: whatever modifications are brought 

 about in the individual in the course of his development are 

 inherited by his offspring. This principle is briefly described 

 as the transmission of acquired characters, in ordinary dis- 

 cussions. It is obvious that /'/ the modifications which the 

 individual animal undergoes because of its response to the 

 living requirements do accrue to the benefit of his offspring, 

 adaptation of species is easily explained. Whatever it is that 

 the individual does and that enables him to continue alive 

 has the virtue of a good habit, or increased skill, or greater 

 strength. According to this idea the children of educated 



