It is of much importance to me to know what Pfeffer means in relation to Wiesners book who has just published a book vivisecting me in the most courteous manner.²

Wiesner looks at Light causing a plant to bend towards it as a direct effect, as much as the lengthening of a bar of iron by heat. I maintain that the light acts as a stimulus & merely tells the plant which way to bend.—³

I thought that Pfeffer was on Wiesner’s side, & I am sure that he was so formerly.— I have written this, because I thought that it would help M^r Patrick⁴ & yourself in understanding Pfeffers notoriously difficult (to Germans) style

C. D.