Originative Factors in Evolution. By J. A. Thomson. 44:9 



into the abyss of extinction, while others with a more fortunate 

 turn rest on a ledge of safety whence new essays of variability 

 begin." But Dr. Gates Mutationist soon takes the place of Dr. 

 Gates Psycho-biologist. After this one exciting glimpse of the 

 organism as climber, we are hurried back to the chemical and 

 physical complexity of the protoplasm and its unique irritability 

 and retentiveness. But we are disposed to linger over the idea of 

 the organism as climber, and the organism here means the genotype, 

 not the phenotype. It is not suggested that the germ-cell is 

 dominated by any purpose of getting to the top of anything, or of 

 circumventing any particular difficulty, but rather that there is 

 inseparable from it a restless experimenting in self-expression, 

 bearing the same relation to the insurgent self-assertiveness of the 

 full-grown creature that the tentatives of dreamland bear to the 

 achievements of open-eyed and deliberate endeavour. , 



The position we are suggesting is that the larger mutations — 

 the big novelties — are expressions of the whole organism in its 

 germ-cell phase of being, comparable to experiments in practical 

 life, solutions of problems in intellectual life, or creations in 

 artistic life. These are accomplislied, everyone knows, by molecular 

 activities in the brain and body, Ijut they are not intelligibly 

 thought of unless we conceive of the organism as a psycho-physical 

 individuality, a mind-body or body-mind, as we will. Similarly 

 it may be that our conception of germinal variability is falsely 

 abstract unless we recognize that germ-cells are living individualities 

 of great complexity telescoped-down into a one-celled phase of 

 being, and that they too make essays in self-expression. 



Perhaps we mislead ourselves by repeating too often, in our 

 elementary teaching for instance, the commonplace that the 

 Metazoon begins its life as a single cell. It is true enough in a 

 way, but certainly not the whole truth. It is no commonplace 

 cell, the gamete. It is an organism in potentid. Within it, in 

 some manner that we cannot begin to image, though we crowd it 

 with factors and genes (the modern successors of Darwin's gemmules 

 and Weismann's determinants), there lies a complex inheritance, 

 unified afresh at the start of each new generation. If an Amceba 

 has a behaviour, as Jennings seems to have proved, may not the 

 much more richly endowed germ-cell of a fruit-fly be allowed the 

 capacity of putting its house in order ? If the Foraminifer 

 Technitella thonipsoni picks up and chooses the materials of its 

 encasement and builds this with what looks like a dawning art 

 may not the ovum of an Evening Primrose be allowed some freedom 

 of internal architecture ? Germ-cells are not corpuscles of 

 undifferentiated protoplasm. They are individualities that live 

 and multiply, that struggle and combine. They are repositories 

 of multiplicate inheritances borne by strangely persistent smaller 



