A COMMENTARY ON LAMARCKISM 



our attention than these four, though of many which have less. 

 It is therefore the generally held view that the case for Lam- 

 arckian inheritance in metazoa is unproven. 



3b. lamarckian inheritance in 

 micro-organisms 



There can be no doubt that a mode of inheritance which 

 satisfies the definition with Avhich this section began is demon- 

 strated by non-cellular organisms. In such organisms the entire 

 body substance participates in the act of reproduction, so that 

 the argument against Lamarckism which turns on the physical 

 inaccessibility of the germ plasm to environmental influences 

 loses much of its force. 



Two examples will be cited. It will be as well to say at the 

 outset that they are founded upon experiments of exemplary 

 design and scrupulous care of interpretation, and are thus 

 wholly free from the taint of muck-and-mystery speculation 

 for which so many Lamarckists have an unfortunate predilec- 

 tion. The intelligibility of the experiments, the fullness and 

 clarity of their exposition, and the hope they offer of rigorous 

 scientific interpretation must not, however, allow us to infer 

 that the modes of inheritance they reveal cannot really be 

 Lamarckian. There is nevertheless an excellent informal reason 

 why to describe them as Lamarckian is singularly pointless. 

 When a phenomenon apparently sui generis is shown to belong 

 to some wider class of phenomena — as, for example, when 

 allergies are shown to belong to the general class of immunity 

 reactions or, to go far back in zoological history, when par- 

 thenogenesis is shown to be a variant of sexual reproduction — 

 then much is gained; for the phenomenon so classified is at once 

 given access to and support from a large and solid body of 

 reasoning and experiment which can be used to suggest new 

 pathways of research and new schemes of interpretation. With 



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