1. The pathology of actinomycosis is briefly summarised, especially its method of invading bone by direct spread.

2. The manifestations, diagnosis and treatment of spinal involvement are considered.

3. The literature is brought up to date with a) a summary of fifteen cases published since the last collected series (forty-seven cases), and b) notes of three cases previously unreported, making, with the case reported on page 215 by Mr Brett, sixty-six cases in the literature.