THE third annual report of the Medical Research Committee, which has recently been published (Cd. 8825: H.M. Stationery Office, price 6d. net.), testifies to a very large amount of work of a varied nature. A notable proportion of this has necessarily been devoted to problems aiising, directly or indirectly, from the war. But the introductory remarks rightly point out that it is meaningless to try to separate the practical from the scientific aspects of any set of investigations. There are many problems, moreover, which the state of war brings into urgency for solution and, at the same time, offers unique opportunities for inquiry.