THE WONDER OF LIFE 583 



may suddenly appear, as it were, full-fledged, with con- 

 siderable perfection from the moment of their emergence, 

 and without intergrades hnking them to the parents. 

 Furthermore, the novel character of the mutant, if we 

 may use the word, is independently heritable and does not 

 blend ; it can be grafted intactly on to another stock, or it 

 can be dropped out as such. Again, mutations are on the 

 whole quaUtative, as contrasted with the quantitative 

 fluctuations. It comes to this, then, that the elusive 

 Proteus, which is the essence of every Uving creature, is 

 ever changeful, sometimes leaping (' mutations ', we call 

 the movements), sometimes taking short tentative steps 

 (' fluctuations ', we call them). 



As to the origin of fluctuations and mutations we must 

 still confess with Darwin that our ignorance is profound. 

 Is it a fundamental characteristic of organisms, that they 

 tend to vary and often to vary creatively ? So much must 

 be allowed for the efiect that fluctuations in the nutritive 

 stream of the body may have in evoking responsive changes 

 in the complex germ-cells. So much must be allowed for 

 the effect that searching environmental changes may have 

 in acting as hberating stimuU to the germ- cells — puUing 

 the trigger of their potentiahty. So much must be allowed 

 for the opportunities afiorded in maturation and fertihza- 

 tion for shuffling the chromosome cards, producing new 

 combinations or dropping out an item altogether. 



Perhaps we can go a step further, recalhng, for 

 instance, what Herbert Spencer emphasized, and what 

 the progress of chemistry since his day has made even more 

 vivid, the tendency in matter to complexify — corpuscles 

 forming atoms, atoms molecules, molecules larger molecules, 

 and so on. Perhaps the living unit, which we know as the 



