The Hemolytic Amboceptor 327 



of substances affecting hemolysis. Fortunately, means are 

 provided for controlling this action, as will be shown below. 



The amboceptor serum keeps indefinitely. When it is to be 

 kept and used from time to time, many experimenters prefer 

 to seal it in a number of small tubes, one of which is opened 

 when the serum is needed, the remainder being kept in an 

 ice-box. Others prefer a stoppered bottle that can be 

 opened and a measured quantity removed as needed. The 

 most convenient way of treating it seems to be Noguchi's 

 method of drying it upon filter-paper. 



For this purpose a good quality of filter-paper is cut into 

 strips 10 to 20 cm. in length and 6 to 8 cm. in breadth, and 

 saturated with the serum, which is permitted to dry. It is 

 well to make a preliminary titration of the serum, for if 

 it be very active it may have to be diluted in order that the 

 piece of dry paper containing the dose be of a size convenient 

 to handle; i drop of serum usually covers about J sq. cm., 

 which is about as small a piece as can be measured, cut, and 

 used with satisfaction if sufficient allowances are to be made 

 for variations in distribution and other conditions that may 

 modify the accuracy of the method. If the unit-strength of a 

 serum be, say, 0.00005 an d the dose o.oooi, water should be 

 added to the extent of about 9 volumes and the mixture 

 gently agitated, so that diffusion may occur without frothing. 

 The diluted serum is poured into a large flat dish, and the 

 strips of paper passed lengthwise and slowly to and fro until 

 not only wet, but thoroughly saturated. Each strip, when 

 the dipping is finished, is held first by one end, then by the 

 other, to drain off the free drops, and then laid flat upon a 

 clean glass plate and permitted to dry. The use of an electric 

 fan is recommended to hasten drying. Paper so prepared 

 contains everywhere about the same quantity of serum. 



The real titration of the serum now begins. With a ruler, 

 one piece of paper is divided into squares of, say, J cm., 

 and a series of tubes prepared with corpuscle suspension and 

 complement and the paper added i square, 2 squares, 

 2j squares, and so on until the unit is determined. When 

 that is achieved, the exact size of the paper containing the 

 unit being known, one sheet of the paper can be ruled into 

 squares of that size or into squares of twice that size since 

 the " dose " is two units at the option of the investigator. 



The sheets of paper are kept in a clean envelope, the quan- 

 tity for each test being cut off as needed. The dry serum 



