Since the observation by Wassermann, Neisser, and Bruck1 of the value of the complement fixation test in lues, the exact nature of the antigenic substance or substances contained in extracts from luetic and normal tissues has received a great deal of attention, and the results appear to show that more than one substance, capable of acting as an antigen, is contained in these extracts. It is the purpose of this contribution to describe briefly a crystal obtained from an alcoholic extract of luetic liver which acts as a very efficient antigen when dissolved in alcohol, and which has not, to my knowledge, been heretofore obtained from such extracts. I regret to state that at the present writing the exact chemical nature of this crystal has not been ascertained, the most that can be said concerning it being that it may belong to the group of crystals which may be obtained from the bile salts.
CRAIG CF. COMPLEMENT FIXATION WITH AN ANTIGENIC CRYSTAL OBTAINED FROM LUETIC LIVER. JAMA. 1910;55(15):1264–1267. doi:10.1001/jama.1910.04330150024009