472 HEREDITY AND DEVELOPMENT 



to competition between homologous determinants in relation 

 to the fluctuating food-supply ? 



Testing the Theory. — The chief objections that have been 

 brought against the theory of germinal selection are, — (i) that 

 it is bound up with a particular notation and theory of develop- 

 ment and evolution — in terms of representative particles or 

 primary constituents, the determinants, which many regard as 

 at once unverifiable and gratuitous ; (2) that it cannot be 

 objectively verified or directly tested by experiment, being, 

 like many other scientific theories, part of an intellectual game 

 with invisible counters ; and (3) that it is gratuitous, since 

 the results of evolution can be interpreted without this extension 

 of the selection-process into the invisible microcosm of the 

 germ-plasm. In answer to these objections, Weismann's 

 original essays and later lectures on germinal selection seem 

 to us quite sufficient, and we must ask the interested reader 

 to consult the original documents and not to base his verdict 

 upon a necessarily brief and incomplete presentation of the case. 

 We offer this commonplace advice because some objectors raise 

 difficulties which a perusal of the original documents would 

 have shown to be inept. 



The progressive course seems to be to take a set of facts 

 from different fields, and to see whether the key which Weismann 

 has gi\'en us does or does not fit. We propose, therefore, to 

 assume the concept of a germinal struggle between primary 

 constituents (not necessarily homologous determinants), and to 

 inquire whether Weismann's suggestion has interpretative 

 value. 



I. No one is very willing to predict the hereditary result of 

 pairing two organisms. Average predictions may be ventured in 

 regard to the issue of a hundred or a thousand pairings. These 

 predictions may be Galtonian or Mendelian, and they may be 

 justified on the average. But individual results continually crop up 

 which are unpredictable ; and even apart from these valuable 



