18 



They remarked that the frequent emergence of II antigen 

 was not to be attributed to a greater strength of their II serum. 



The following is the method employed by Truche for the 

 preparation of his sera.* The deposit from cultures 15-18 hours 

 old is treated with alcohol-ether, dried in vacuo, and rubbed into 

 a very fine powder. His horses receive, intravenously, 2 centi- 

 grammes on 10 successive days; after 10 days rest, the horse is 

 bled. A fortnight later, gradually increasing doses are given 

 on 4 four successive days and are followed by 6 days' rest ; on 

 the 11th day the horse is bled. The process of immunisation is 

 then continued as before. He tests his sera by agglutination, 

 fixation of complement, and protection. For the last test he 

 inoculates 0*1 c.c. of serum subcutaneously into a mouse and 

 the next day gives a subcutaneous dose of 0*01 c.c. of the homo- 

 logous culture, the virulence of which must be such that the 

 control is killed by a millionth of a c.c. or less. He does not 

 find that the preventive or curative powers of his sera run parallel 

 with their agglutinating capacities. Following the " mosaic 

 pattern " conception, he considers that the organism responds 

 to the accessory antigens and not only to the dominant antigen. 

 u The serum obtained therefore offers a zone of protection which 

 " is certainly wider than that of the dominant antibody. Notably 

 " with man, a serum possessing a strong preventive power is active 

 44 against the homologous type and also against certain heterologous 

 " types ; hence it is that a certain number of cases of pneumonia 

 " of Type III have been cured by serum I and, more particularly, 

 " by serum II." 



Several French clinicians have made favourable observations 

 as to the efficacy of Truche's sera. 



Difficulties. 



Whilst appreciating the value of the progress which has 

 been made, it must be admitted that the present position is 

 unsatisfactory. The Rockefeller investigators can only offer serum 

 therapy if the case is found to be due to Type I ; in that event, 

 their experience is that large and repeated intravenous injections 

 of specific serum will bring down the mortality due to this type 

 from about 25 to about 10 per cent. Diagnosis of the type 

 should be made at an early stage of the disease and treatment 

 should follow immediately. But, in hospitals, patients are often 

 in an advanced stage on arrival ; and, owing to the special skill 

 and care which are required and to the very large quantities of 

 serum needed, this treatment is not likely to be readily adopted 

 by the general practitioner. 



If the precise antigenic characters of the infecting strain of 

 pucumococci are all important, one can understand that it would 

 be difficult, if not impossible, to provide therapeutic sera which 

 would be useful for infections with "atypical" strains; but. 

 even on this assumption, there is no generally accepted explana- 



* Ann. de VInat. Pasteur, XXXIV, p. 98. 1920. 



