242 THE ACUTE PNEUMONIAS 



The difficulty of interpreting the various serological facts 

 observed in pneumonic conditions has led Lamar to investigate 

 the action of certain chemical bodies, belonging to the soaps, on 

 pneumococci. Welch long ago observed changes in the proto- 

 plasm of pneumococci in pneumonic exudates, pointing to the 

 occurrence of lysis. Lamar has found that pneumococci treated 

 with sodium oleate and especially with potassium soaps of acids 

 having a high iodine value — e.g., linoleic and linolenic acids — 

 undergo morphological changes and become more subject to 

 autolysis and more sensitive to the lytic action of sera, the latter 

 being especially evident when immune sera are employed. The 

 action of the soap is probably exerted on the lipoidal moiety of 

 the bacterial cells, which are thus rendered more pervious to the 

 serum constituents. There is evidence, however, that the protein 

 constituents of sera exercise an inhibitory effect on the lytic action 

 of the soaps, and Lamar has made the interesting observation that 

 this inhibitory action can to a certain extent be neutralised by 

 the use of boric acid. These observations are of the highest 

 importance, and there is some experimental evidence that they 

 may form the basis for a therapeutic treatment of pneumococcic 

 infections. That they have a bearing on the explanation of 

 natural recovery from such infections is indicated by the fact that 

 in inflammatory exudations soaps form a definite constituent. 



Vaccine therapy in pneumonia. — It may be stated here that 

 vaccine therapy has been applied in the treatment of pneumonia, 

 20 to 30 millions of a stock vaccine being administered pending 

 the preparation of an autogenous vaccine from cultures of the 

 infecting strain made from material obtained by puncture of the 

 pneumonic lung. Needless to say, the greatest care and judg- 

 ment are necessary in the use of such vaccines. In certain 

 cases there has been apparently a good result, but in others 

 there is no evidence that the chance of survival has been greater 

 than when ordinary treatment is applied. Something may be 

 said for a combined treatment with serum and vaccine by the 

 use of sensitised dead bacteria on the lines already described in 

 dealing with streptococcic infections. Further, Kosenow has 

 used as a vaccine pneumococci from which certain toxic properties 

 have been removed by treatment with normal saline. 



Prophylactic Vaccination. — In the South African mines a special 

 situation exists in consequence of the great susceptibility to pneumonia 

 occurring in the native labourers, who are chiefly recruited from sub- 

 tropical regions. As the case incidence may run from 30 to 150 per 

 thousand per annum, and the mortality from 10 to 30 per thousand, 

 the disease is a very serious one. Almroth Wright introduced prophylactic 

 vaccination, and Lister, founding on his investigations (v. supra), pre- 



