SERUM THERAPY 143 



In infants and young children, about 15 to 20 

 c.c. of fluid may be withdrawn, and in adults, 40 

 to 60 c.c; the fluid being allowed to flow until 

 the cerebrospinal fluid pressure falls to normal : 

 one drop from the needle every 3 to 5 seconds 

 being about normal. 



Blood Pressure Guide. In the administra- 

 tion of this serum, the blood pressure method of 

 control, as recommended by Flexner and by the 

 New York City Department of Health, is the 

 safest means of estimating the amount to be 

 given; and if only a small amount of cerebro- 

 spinal fluid is obtained, or in cases of a dry 

 puncture, this method is of especial value. It 

 has been noted that the blood pressure falls 

 during the injection of the serum and that the 

 degree of fall may be used as a guide to the 

 quantity of serum that can be safely injected. 

 As a result of observations in many cases, it has 

 been found that a total fall of 20 m.m. of mer- 

 cury in a person with an initial blood pressure 

 of 110 to 120 m.m. indicates that the further in- 

 jection of serum should be stopped. The de- 

 gree of fall in blood pressure that may be safely 

 allowed during the introduction of serum can be 

 fairly well determined by considering a fall of 



