BACTERIOLYSIS AND ALLIED PHENOMENA 



i8 7 



a deposit of undissolved corpuscles, and when there is no haemo- 

 lysis the fluid will be untinged. 



Modifications of the process are numerous, and almost every 

 investigator has his own. Thus it is very convenient to make the 

 mixtures by means of one of Wright's pipettes. The whole is 

 sucked into the pipette, which is sealed and incubated. At the 

 end of the process the mixture may be expelled on to white filter- 

 paper. Any unaltered corpuscles will form a solid dark deposit in 

 the centre of the drop, whilst the fluid which soaks through the 

 paper will be tinged or colourless, according to the amount of 

 haemolysis which has taken place. The amount of haemolysis may 

 also be determined more accurately by comparison of the super- 

 natant fluid with a series of colour-standards previously prepared. 

 The mere presence or absence of the phenomenon may be readily 

 shown by dropping some of the fluid on to filter-paper. 



The amount of immune body present may be determined by 

 some such process as the following : In each of a series of narrow 

 test-tubes (having a mark to indicate 2 c.c.) is placed i c.c. of the 

 emulsion of corpuscles, and then varying amounts of the heated im- 

 mune serum e.g., o'ooi c.c., 0-0025 c.c., 0*005 c<c -> e ^ c< ' or more if 

 the serum be a weaker one. As these small amounts are not easy to 

 measure accurately, the serum may be diluted ten or a hundred 

 times with normal saline solution and suitable multiples, these 

 amounts taken in the case of the smaller doses. The actual 

 measurements are done with graduated pipettes, which can be 

 procured from any instrument-maker. The complementing serum 

 is then added : the amount necessary to dissolve i c.c. of fully- 

 sensitized serum should have been previously determined by a 

 few rough tests (we will suppose it to be 0-2 c.c.). Lastly, sufficient 

 normal saline is added to bring the volume of each tube up to 2 c.c., 

 and the whole series treated as above. Thus 



