At CD’s request he has read Malcolm Guthrie’s book [On Mr Spencer’s formula of evolution (1879)], which is a critique of First principles. He finds it a helpful clarification of Spencer’s views; however, it is as pseudo-scientific as the book it criticises.

Thanks for Erasmus Darwin.

Violetta Darwin is near death.

Gives his opinion on vivisection. CD detests cruelty but believes that physiology "is one of the most important sciences" and that it cannot progress without experiments on living animals.