18 president's address. 



whom depends the future of the race is cut off from all active experience 

 of life : she is a mere reproducing machine, housed, fed, and protected by 

 the workers. But these, on whom falls the burden of the struggle for 

 life and the experience of the world generally, are sterile, and take no 

 direct share in the reproduction of the species. The queen represents 

 Weismann's germ-plasm, the workers are the body or soma. Now 

 imagine the colony exposed to some injurious change in environment ; 

 the salvation of the species will depend on whether or no an improved 

 pattern of worker can be produced. This depends on the occurrence of 

 appropriate variations, so that the queen bee and the drones, on whom 

 this depends, are of central importance. On the other hand any change 

 occurring in the workei's— for instance, increased skill due to practice in 

 doing their work or changes in their structure due to external conditions — 

 cannot possibly be inherited, since workers are absolutely cut off from the 

 reproduction of the race. According to Weismann, there is precisely the 

 same bar to the inheritance of somatic change. 



The racial or phyletic life of all organisms is conceived by him as 

 a series of germ-cells whose activity ia limited to varying, and whose 

 survival in any generation depends on the production of a successful soma 

 or body capable of housing, protecting, and feeding the germ-cell. Most 

 people would a priori declare that a community where experience and 

 action are separated must fail. But the bee's nest, which must be 

 allowed to be something more than an illustration of Weismann's theory, 

 proves the contrary. 



It is clear that there must be war to the knife between the theory 

 of Weismann and that of the somatists — to coin a name for those who 

 believe in the inheritance of acquired characters. A few illustrations 

 may be giveii of the strength of Weismann's position. Some trick or 

 trivial habit appears in two successive generations, and the son is said to 

 inherit it from his father. But this is not necessarily a case of somatic 

 inheritance, since according to Weismann the germ-plasm of both father 

 and son contained the potentiality of the habit in question. If we keep 

 constantly in view Weismann's theory of continuity, the facts which are 

 supposed to prove somatic inheritance cease to be decisive. 



Weismann has also shown by means of his hypothesis of ' simultaneous 

 stimulation ' ' the unconvincingness of a certain type of experiment. 

 Thus Fischer showed that when chrysalids of Atxtia caja are subjected to 

 low temperature a certain number of them produce dark-coloured insects ; 

 and further that these moths mated together yield dark-coloured offspring. 

 This has betn held to prove somatic inheritance, but Weismann points 

 out that it is explicable by the low temperature having an identical effect 

 on the colour-determinants existing in the wing-rudiments of the pupa, 

 and on the same determinants occurring in the germ-cells. 



It does not seem to me worth while to go in detail into the eyi- 



' I borrow this convenient expression from Plate's excellent book, Ueher die 

 Bedeutung des JJarrvin'soheii Se'leotionspritioipt, 1903, p. 81* 



