58 GERMINAL SELECTION. 



epigenesis from absolutely homogeneous and not 

 merely like units is not thinkable. 



All value has been denied my doctrine of determin- 

 ants 1 on the ground that it only shifts the riddles of 

 evolution to an invisible terrain where it is impossible 

 for research to gain a foothold. 



Now I have indeed to admit that no information 

 can be gained concerning my determinants, either with 

 the aided or with the unaided eye. But fortunately 

 there exists in man another organ which may be of 

 use in fathoming the riddles of nature and this organ 

 which is called the brain has in times past often borne 

 him out in the assumption of invisible entities entities 

 that have not always proved unfruitful for science by 

 reason of that defect, in proof whereof we may in- 

 stance the familiar assumptions of atoms and mole- 

 cules. Probably the biophores also will be included 

 under that head if the determinants should be ad- 

 judged utterly unproductive. But so far I have always 

 held that assumptions of this kind are really produc- 

 tive, if they are only capable of being used, so to 

 speak, as a formula, whereby to perform our compu- 

 tations, unconcerned for the time being as to what 

 shall be its subsequent fate. Now, as I take it, the 

 determinants have had fruitful results, as their appli- 

 cation to various biological problems shows. Is it no 

 advance that we are able to reduce the scission of a 

 form of life into two or several forms subject to sep- 

 arately continued but recurrent changes, I refer to 

 dimorphism and polymorphism, that we are able to 

 reduce such phenomena to the formula of male, female, 

 and worker determinants? It has been, I think, ren- 



1 Oscar Hertwig, Zeit- und Streitfragen der Biologic, Jena, 

 1894. 



