PATHOLOGY OF PNEUMOCOCCUS INFECTION 239 



sera. The Kockefeller serum is prepared by immunising horses 

 first with dead cultures ; daily injections are given for six days, 

 followed by an interval of a week, then six further daily injec- 

 tions are given ; it is sometimes necessary to follow thesej up by 

 the use of living organisms. Uniformity of strength in successive 

 sera thus prepared is secured by determining the largest amount 

 of an eighteen hours' culture against which - 2 c.c. of the serum 

 will protect a white mouse, — a comparison with the effects of the 

 same amount of a standard serum being at the same time made. 

 In the therapeutic application of the serum in a case of Type I. 

 pneumonia large quantities must be used, and it is therefore a 

 necessary preliminary to determine whether the patient exhibits 

 hypersensitiveness to horse serum, and to desensitise him if this 

 exists (see chapter on Immunity). If the way be clear, the 

 serum, diluted with an equal amount of sterile saline made with 

 freshly distilled water, is administered by the intravenous 

 method — 10-15 c.c. being given at the rate of 1 c.c. per minute 

 — changes in the heart's action and in respiration and the 

 occurrence of urticaria being watched for, and the treatment 

 being suspended for a quarter of an hour if untoward symptoms 

 seem to increase ; if this does not occur, the remainder of the 

 first dose may be given during fifteen minutes. The initial dose 

 should be from 90-100 c.c, and the injections ought to be re- 

 peated every eight hours till about 250 c.c. serum have been 

 given. Very soon after commencement of treatment the tem- 

 perature may rise, but this is quickly succeeded by a fall, with 

 improvement in the patient's general condition, stoppage of ex- 

 tension of the lung lesion, and prevention of invasion of the blood 

 by the pneumococci. The effects of the treatment so far have been 

 satisfactory, — of 107 cases treated in the Rockefeller Institute 

 Hospital up to October 1917 only 7 "5 per cent, died, as compared 

 with a mortality of 25 to 30 per cent, in cases of Type I. pneumonia 

 before the serum treatment was introduced. Up to the present 

 no means of treating pneumonia of Types II. and III. by serum 

 methods have been found practicable, and, as has been stated, the 

 pneumococci of Type IV. do not yield a group anti-serum. 



The Pathology of Pneumococcus Infection. — The effects of 

 the action of the pneumococcus, at any rate in a relatively 

 insusceptible animal such as man, seem to indicate that toxins 

 may play an important part. Pneumonia is a focal disease 

 which presents at the same time the character of an acute 

 poisoning. In very few cases does death take place from the 

 functions of the lungs being interfered with to such an extent 

 as to cause asphyxia. It is from cardiac failure, from grave 



