5 oo SCIENCE PROGRESS 



(3) It depends on the temperature, which may be constant, 

 or may be allowed to vary. 



Thus (f>(t) is a function oi the time which, in the present state 

 of our knowledge, we cannot define. Under the conditions of 

 experiment all the leucocytes were originally empty, hence 

 for (m = o), 



the existence of groups containing a minus number being im- 

 possible. 



From these two equations we can eliminate the time, and 

 consequently all the unknown factors ; and we have : 



dy 



— = y» - , - ym 

 uz 



where z = \og e — 



a being the initial number of empty leucocytes. 

 From this equation we have : 



yi = y z 

 ya=y ~, 



z 2 



nua 



ym=yoi_ 



m! 



Now the average content is 



oy + 'yi + 2y,, + my m + . . . 



y + yi + y* + y» + — y* + . . . 



z 2 z 3 



_ yo(z + 2 jr + 3 jr + • 



y (i + z + ^-+ — 

 = z 

 = log. - 



This is, then, the relation between the average content and 

 the proportion of empty cells, and gives a practical method of 

 estimating the average which is of considerable value when the 

 proportion of empty cells is not too low. 



