THE INHERITANCE OF ACQUIREMENTS 7.5 



stance, a man acquires inininnity to a disease. That 

 is to say, his body-cells, being attacked by microbes, 

 undergo a change, whereby they constantly produce 

 an "anti-toxin" which renders the further attacks of 

 these microbes futile. The production of this anti- 

 toxin depends upon the previous production by the 

 microbes of a toxin which circulates in the blood and 

 lymph, and somehow causes the cells which it en- 

 counters to acquire the power of producing the anti- 

 toxin. Now the toxin, in such a case, may be carried 

 to the germ-cells, and they, like the body-cells (which 

 were originally derived from similar germ-cells) may 

 undergo the changes which enable thum to produce 

 the anti-toxin whenever the appropriate stimulus is 

 forthcoming. Plainly, in such a case, we can con- 

 ceive it possible that the individual produced from 

 one of these ^^erm-cells should be immune to the 

 disease in question. His father's acquired imnumity 

 will thus have been transmitted to him. 



Similarly, other instances can be quoted where the 

 modus operandi of the inheritance of an acquire- 

 ment can be definitely conceived. Now we nuist 

 remember that the Weismannian denial of the 

 transmissibility of acquired characters was based 

 not upon observation, but upon the doctrine of the 

 continuity of the germ-plasm. On the Darwinian 

 theory of pangenesis, the -Mo^i-transmissibiHty of 

 acquired characters was inconceivable. On the 

 theory of the continuity of the germ-plasm, their 

 transmissibility was alleged to bo incouceivabio. 

 When, however, cases are cited wherein the trans- 

 missibility — whether it occurs or not — is conceivable, 

 as in the case quoted, the a pHoin argument falls to 



