Will write again to Tyndall about odours.

Asks for the circumstances under which WO saw a man arrested for murder; quotes from notes he made from WO’s conversation [Expression, p. 294].

Also would like to quote WO on the expression of resignation by persons about to undergo serious operations [Expression, p. 271].

Thanks WO for his replies [to 7551]. Discusses the open mouth in surprise; asks WO to investigate its function in hearing and breathing.

Asks why deaf persons generally keep mouths open.

Agrees that in a deaf person the jaw may fall because of concentrated attention.

In surprise, mouth is opened suddenly and chest filled with air. This expression occurs in all parts of the world. Odd that so simple a movement is so perplexing to understand.

Asks WO to act out the sudden discovery of a dreadful object and to observe whether his platysma contracts. CD has found in his notes that it is never contracted in cases of severe dyspnoea [Expression, p. 301].

Thanks WO for his reply to letter of 26 March. Has tried several people and platysma seemed to act, but it is difficult to observe when they shudder.