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



reason for the lessened virulence of older cultures, the increased 

 phagocytosis must also be accompanied by an increase in the 

 intracorpuscular digestion of the englobed bacteria. 



The question of the intracorpuscular digestion of the bacteria 

 was therefore bracketed with that of opsonisation. 



Age of culture. 



Cocci per leucocyte. 



Stained and counted 

 six weeks later. 



1 day 



25 

 35 

 28 

 22 



19 



2 days 



3 days 



23 

 19 



4 days 



15 







We see from this experiment that the bacteria of the 24 hours' 

 culture are more feebly opsonised than those of the 48 hours'; it 

 is assumed, therefore, that they are more virulent. The counts 

 made at the later date show that intracorpuscular digestion has 

 occurred. 



A confirmation of the greater digestibility of the englobed 

 bacteria was made about eighteen months afterwards, but the 

 experiment took a different form, as the table will show. 



Cocci per leucocyte. 



Time of incubation in minutes... 5 ... 10 ... 15 ... 30 



Age of culture— 1 day 3-6 ... 6'5 ... 8*5 ... 9*5 



,, 2 days 5'6 ... 8'5 ... 10'8 ... 13*4 



„ 3 days 5-1 ... 73 ... 9-0 ... 11*4 



Again we see the more feeble opsonisation of the bacteria of 

 the 24 hours' as compared with those of the 48 hours' cultures. 

 If the results are plotted in such a way as to make the ages of 

 the cultures the abscissa, and the phagocytic indices or cocci per 

 leucocyte the ordinates, and the points are joined by straight 

 lines, we get four angles, one for each time of incubation. On 

 the paper which was used the angles measured approximately — 



5 minutes' incubation 120° 



10 „ „ 102° 



15 „ „ 90° 



30 „ „ 730 



