224 THE PHILOSOPHY OF BIOLOGY 



regarded (in 1883) as immutable things, preserving 

 their individuahty even when they were associated 

 together as compounds, so Weismann and his followers 

 looked upon the different kinds of life-substance con- 

 tained in the chromatic matter of the nucleus as 

 immutable and immortal living entities. Associated 

 together in indeiinitely numerous ways by sexual 

 conjugation, the}^ may build up indefinitely variable 

 living structures, but they remain individualised and 

 lying side by side in the germ-plasmata of organisms, 

 just as the atoms were supposed to lie side by side 

 in the chemical molecule of the inorganic compound. 



If these speculations were true, a change of mor- 

 phology or functioning, acquired by the body, or 

 somatoplasm, could not possibly be transmitted to 

 the progeny of the organism, for by hypothesis the 

 germ-plasm cannot be affected by external changes, 

 and it is only the germ-plasm contained in the 

 spermatozoon of the male parent, or in the ovum of 

 the female, that shapes and builds the body of the off- 

 spring. As if this were not enough, Weismann and 

 his followers argued that the transmissibility of a 

 somatic change to the germ was inconceivable. Why ? 

 Because the germ-cells are apparently simple : they 

 are only semi-fluid protoplasmic cell bodies and 

 nuclei, not differing appreciably from the cell bodies 

 and nuclei of the somatoplasm (by hypothesis, it should 

 be noted, the difference is profound). There are no 

 structural connections — no nerves, for instance — 

 which join together the cells of the bodil}^ tissues 

 with the parts of the germ and transmit changes in 

 the former to the latter. How, then, could a somatic 

 change affect the germ so that when the latter developed 

 into an organism this particular change became repro- 



1 We know now that this statement is not quite accurate. 



