the constant, ^~ ' is negligible, and we may say that figures 



670 Form assumed by Red Corpuscles of the Blood. 



the assumption that the thickness of those parts of the disk 



near the centre lies within a range of values for which T 



decreases uniformly with y, we can put T = % (where k is a 



constant) and proceed from equation (12). Doing so we find 



the relation 



y y . . 2T 



J =cos ^_X smt __ 



or using fig. 2 



^ = cos X (tan % - tan a) - ^ . 



T 

 Now y is a linear magnitude which approximates to the 



critical thickness, and so must be much smaller than r ; so 



2Tc 

 kr 



of the form indicated above are possible if p is positive near 

 B, i. e. if 



tan x > t an a, 



or ^ > a. 



Now such a condition is easily satisfied for some distance 

 from B. Of course, as we must ultimately reach a point at 

 which p becomes negative, % must decrease faster than a. 

 A point of inflexion of course would occur at a position in 

 the neighbourhood of the point where % = «, and the analysis 

 indicates that this would happen even before we reached 

 thicknesses greater than the critical value. 



One could reach a similar conclusion, without assuming 

 any special relation between T and y, except T = T /(y), 

 where /(y) is positive and increases asymptotically to the 

 value unity, as y approaches half the "critical thickness." 



An application of equation (12) would give 



- = cos Y -rvH — sin yjr . 



p f(v) ' x r f(y) 



Close to the central portions of the disk the first term is 

 positive, and will decide the sign of the right-hand expression, 

 the last term being negligible as before, on account of the 

 comparative largeness of r. 



