Remarks on the Nature and Definition of Species. 49 



sistent specific framework, liable, it is true, to phenot\-pic dis- 

 tortion or to mutational collapse, but itself incapable of any 

 permanent alteration from without. 



Now it cannot be too strongly insisted that such an ideal is 

 wholly chimerical. All experience, now confirmed and sub- 

 stantiated b}' phvsico-mathematical demonstration, leads to the 

 conclusion that there are no units in nature which possess an 

 absolute value, without relation to the circumstances in which 

 they occur and that to search for them is a waste of time. It is 

 only another phase of the secular Quest of the Absolute, as 

 illusory as the Philosopher's Stone. To accept such an ideal is 

 to abstract the species from its en^"ironment and endow it ^^ith 

 a transcendental entity of its own, in the guise of a pure force- 

 system divorced from all relation to the material substrate. 

 Moreover this system, admittedly invohing an almost infinite 

 complexity of interactions, is figured as permanent, but in a 

 wholly transcendental mode, as a mediate factor threading 

 through a complex series of immediate changes in the gro^^•th 

 form, never directly demonstrable but always present as an 

 abstract bond, linking together all the phases of the change- 

 series. 



It may be objected that permanency of constitution is de- 

 monstrable by permanence of reaction under standardised con- 

 ditions. Supposing then a certain organism A to be grown under 

 two distinct sets of conditions i and 2, in which it develops \\ith 

 two distinguishable facies k and m. 



(k) (m) 

 If transplanted, reversal occurs; 



{k)y(Jm) 



[k] (m) 



and it may be argued that in this way the constitution of the 

 organism is sho\Mi to be unchanged throughout. This however 

 is a pure assumption under the circumstances. All that our 

 observation shows us is that the strain is capable of certain 

 changes, that in one set of circumstances these changes may be 

 reversed and that in another set of circumstances they may be 

 perpetuated. What the nature of these changes may be and 

 whether they leave unaffected any permanent specific frame- 

 w"ork underh-ing them is not brought into the evidenc a"" all. 

 \\'e cannot go beyond the obser\-ed fact that the organism is 



