686 OPSONISATION FROM A BACTERIAL POINT OF VIEW, ETC , 



The differences in the counts are more pronounced than in the 

 preceding table, while the lesser differences in the 50 counts are 

 corroborated. 



In relation to the differences in the phagocytic activities, it 

 may be noted that Bushnell* brought forward evidence to show 

 that the leucocytes varied in their capacities for absorbing 

 bacteria, and that Briscoe* showed that of all the polymorpho- 

 nuclears those with tripartite nuclei are more active than others 

 with greater or less divided nuclei. 



The regularity of phagocytosis. — It has been found necessary 

 when determining the opsonic or the phagocytic index of a serum 

 to count at least 100 polymorphonuclears. It is even deemed 

 advisable to enumerate 200, and although this will give a truer 

 result, it will occupy more time than is, perhaps, warranted. 

 Even the counting of 100 cells may occupy from 20 minutes to 

 half-an-hour. If, therefore, some of this time could be saved by 

 determining the conditions of phagocytosis so that a smaller 

 number of leucocytes could be depended upon to give a true 

 index, it would be advantageous to all opsonic workers. 



The most important factors which contribute to produce 

 differences in the phagocytic indices and the rate of phagocytosis 

 are probably the following : — 



1. The nature of the white corpuscles. 



2. The method of smearing and segregation of the white 

 corpuscles. 



3. The nature of the fluid in which phagocytosis takes place. 



4. The duration of phagocytosis. 



5. The temperature of phagocytosis. 



6. Other known factors such as the serum, intracorpuscular 

 digestion, etc. 



The first two have been already considered; the last need not 

 be discussed. The third factor, if it were fully investigated, 

 would involve a vast amount of work, possibly without any com- 

 mensurate result. However, the question was examined in part 

 with numbers 4 and 5. 



* Brit. Med. Journ. Nov. 16th, 1907, L422, 1423. 



