262 PASSIVE IMMUNIZATION 



every case before an ultimate verdict upon the subject can be 

 reached. 



A serum which possesses a high degree of protective as well as 

 curative value against the common strains of pneumococci, in the 

 animal experiment, is at present prepared under Neufeld's direction 

 by the Serum Institute of Saxony, and may be recommended for 

 use in infections with the corresponding strains. Its titer is such 

 that 1 c.c. will protect 5000 grams of body weight (tested against 

 white mice weighing from 18 to 20 grams) against 0.1 to 0.0001 c.c. 

 of a pneumococcus bouillon culture, the fatal dose being 0.000001 

 or less. Neufeld and Handel point out that it is essential to test 

 out the serum against large or medium doses of the organism, as the 

 values obtained in the case of small doses do not apply to correspond- 

 ing multiples. Of a serum, for example, which would protect in a 

 dose of 1 c.c. against the minimal fatal dose, 5 c.c. would not neces- 

 sarily protect against five multiples of the fatal dose and so on. They 

 ascertained that there is a certain threshold of action beyond which 

 a given dose will protect against many multiples (up to a million) 

 of fatal doses, while below this point the activity of the serum 

 rapidly diminishes and may indeed be nil. 



In a concrete case the question naturally arises whether the type 

 of the infection corresponds to the strains with which the serum was 

 produced. To this end it is recommended to inject a mouse with a 

 small quantity (0.5 c.c.) of the patient's sputum to which one titer 

 dose of the serum has been added. If then the animal does not 

 succumb within the next twenty-four hours we may assume that the 

 serum is homologous to the type of the infection and would hence be 

 applicable. 



Mode of Action. As regards the mode of action of his antipneumo- 

 coccus serum Neufeld lays special stress upon its bacteriotropic 

 effect. It is possible, however, that it may have a certain bacterio- 

 lytic as well as antitoxic component as well. 



Dosage and Mode of Administration. As the absorption from the 

 subcutaneous tissue is notoriously slow the serum should be injected 

 intravenously whenever possible, or intramuscularly, if for any 

 reason (as in young children) the other route is excluded. The initial 

 dose for an adult is 40 to 50 c.c., and for children one-half of this 

 quantity, and may be repeated on the following day. If the patient 

 has been previously treated with horse serum it is recommended 



