186 THE ANATOMY OF SCIENCE 



factors here, and a thoroughgoing follower of 

 Weismann might even claim that, conversely, 

 the invention of the flour mill and the oven had 

 followed upon the diminishing strength of the 

 tooth, necessity being the mother of invention. 



On the whole the disbelievers in transmission 

 of acquired physical characteristics, in the nar- 

 row sense in which we are now using the term, 

 seem to have much the better of the argument. 

 They are, moreover, supported not only by ex- 

 periment and observation but also by the whole 

 development of biological theory. 



In the beehive with its thousands of individu- 

 als onl}'^ one member (except in the rare case 

 when a worker lays eggs) becomes the mother 

 of the next generation. So it appears in plants 

 and animals there are myriads of cells which 

 do the work of the body, but only a few, the 

 germ cells, that serve to perpetuate the species. 

 Unless therefore there is a higher degree of 

 intercommunication between the two types of 

 cells than is commonly supposed, we should 

 hardly expect anything that happens to the 

 worker cell to have any marked effect upon in- 

 heritance. This idea of the independence of the 

 "germ-plasm" is entirely in accord with the re- 

 cent developments in biology to which the redis- 



