Action of Sodium Glycocholate. 



95 



produced depends on two factors : (1) the amount of serum albumin added ; 

 and (2) the time for which it remains in contact with the cells. A suspen- 

 sion thus made insensitive is not resensitised by washing once in the centri- 

 fuge : repeated washings may render it sensitive to some degree. 



The Protective Power of Blood Serum. 



As serum blood albumin has tins effect, it might be supposed that blood 

 serum itself had a similar effect. The following typical experiment shows 

 this clearly : — 



Tube 1. — 1 c.c. suspension 0'02 c.c. serum. 



Tube 2. — 1 c.c. suspension O015 c.c. serum. 



Tube 3. — 1 c.c. suspension - 01 c.c. serum. 



Tube 4. — 1 c.c. suspension 0'005 c.c. serum. 



Allow the tubes to stand 5 minutes. The suspension used is a sensitive 

 one. Test the suspensions to see if they are sensitive or not. 

 The typical result is as follows : — 



Table X. 



When t = 18 ; 8 — 100 : +0 - 4 c.c. 1 per cent, albumin. 



Tube. 



T. 



Tube. 



1 t$ "':} t. 



Control 



15 seconds. 



3 



6 minutes. 



1 



20 minutes. 



4 



25 „ 



2 



15 







The serum thus renders a sensitive suspension insensitive. Such an insensi- 

 tive suspension is however restored on washing the cells in the centrifuge ; an 

 occurrence which is not found in the protection conferred by serum albumin, 

 and suggesting that the protection is conferred in different ways in the two 

 cases. The protection is conferred not by fresh serum only, but by preserved 

 serum, kept for over 18 months by the method of Leers (4). 



Animal Experiments. 



It is confirmatory of these experiments that the protective action of serum 

 albumin occurs in vivo as well as in vitro. 



If a rabbit be taken and from a vein a small quantity of blood (0 - 05 c.c.) be 

 drawn into citrated saline, the suspension resulting after washing these cells 

 — preferably once — is sensitive to the mixture of glycocholate and serum 

 albumin. If now 5 c.c. of a 2 per cent, serum albumin solution in saline be 

 injected into a vein, and blood withdrawn from a distant vein about 

 5 minutes later, the suspension prepared from this blood will be insensitive. 



