672 OPSONISATION FROM A BACTERIAL POINT OF VIEW, ETC., 



were obtained at different times from pus, and, as the following 

 shows, these races were opsonically identical. 



Cocci per leucocyte. 



Race (OR) eight months after isolation 25 



(NR) two weeks ,, ,, 26 



(OR) ten months ,, ,, 31 



(NR) ten weeks ,, ,, 31 



(AR) one day ,, ,, ... 32 



Experience has led us to know that the virulence of bacteria 

 generally diminishes while they are maintained under the 

 artificial conditions that obtain in growing them in the laboratory. 

 The opsonic identity of these races is at variance with this idea 

 regarding the loss of virulence unless it be that there is no 

 relation between virulence and power of being opsonised. 



Moist and dry groivths of bacteria. — In the belief that the 

 bacteria in the dry upper portions of an agar slope might produce 

 an amount of opsonisable substance different from the bacteria 

 in the moist lower portions, the following experiment was made : 



Cocci per leucocyte. 



Moist lower portion of slope in normal saline 27 



Dry upper portion of slope in normal saline , 22 



Washed cells of moist portion in normal saline 27 



Washed cells of moist portion in its own condensed water, diluted 



1 : 24 with normal saline.., 27 



This result led to the following set of experiments, which were 

 made at different times : — 







1 



3occi 



per 



eucocyte. 







Dry upper cells of agar slope 



Moist lower cells of agar slope 



ii. 



19 

 22 



iii. 



8 

 9 



iv. 



10 



8 



v. 



3 



3 



vi. 



5 

 5 



vii. 



10 

 10 



viii. 



5 

 4 



ix. 



8 



7 



It is evident from these that when moderately strong suspen- 

 sions of bacteria are used, the cells of the moist growths are more 

 completely opsonised than the bacteria of the dry cultures. 

 When, however, the suspensions are not so opaque, the differences 

 in the opsonisation are not evident. 



