Letter from Rosemary Biggs to Dr Stanley Wray, General Hospital, providing some information on two types of concentrated A. H. G. - Human A. H. G. made by the Lister Institute and Animal A. H. G. available through the General Hospital for specific suitable cases. Indicates that these are available in small amounts for the treatment of specific patients. Refers to the variability of the A. H. G. content of frozen plasma