"trying to his sensitive liver"

Claude Galien by Pierre Roche Vigneron (around 1865)
Public DomainClaude Galien by Pierre Roche Vigneron (around 1865)
Historically, the liver was regarded as the seat of the passions, a view which had its basis in the writings of the Roman physician Galen. In saying something is trying to the Assistant Commissioner’s liver, Conrad is implying that it gets on his nerves.