468 



PHAGOCYTOSIS OF SOLID PARTICLES. II 



D= 1 + 



5.1 V 

 pi 



Substituting in this equation values for the average velocities and 

 average diameters of the two suspensions (0.87 ± 0.12 and 2.19 

 ± 0.18 cm. per hour for the 3.2m and 4.7At respectively), and solving 

 for D, we obtain 1.43 ± 0.06 and 1.50 ± 0.04. This is the density 

 with capillary spaces full of water, 



TABLE I.* 



Chances of Collision between Leucocytes and Carbon Suspensions. 



* Chances of collision, R, with cells of the two carbon suspensions. The group 

 diameters were obtained by averaging the squares of the individual diameters as 

 measured in the microscope. Group velocities were calculated in proportion to 

 the squares of the group diameters and so that their weighted average velocity- 

 should be equal to the average velocity of the suspension as determined experi- 

 mentally by the stop-cock method; i.e., to 0.87 ± 0.12 and 2.19 ± 0.18 cm. per 

 hour for the 3.2 /i and 4.7^ suspensions, respectively. The R group or chance 



of collision is given by the formula 



p 



R group = {Ria Pa + Rih Pb + Ru Pc ) Tprz 



lUU 



where P equals the per cent of particles or cells in designated group, subscripts 

 a, b, and c refer to the three groups of cells, and the numerical subscripts refer to 

 the groups of particles. 



From these figures may be calculated the cubic centimeters of 

 capillary space, x, in the carbon per gram of dry weight, as follows: 



1.81 + 1.81a; 



2? = 



1 + 1.81a; 



