The Shape of the Human Red Blood Corpuscle. 169 



moment or two does not apparently increase the number of 

 crenated corpuscles nor the number or size of the rouleaux, 

 indicating that these phenomena are not dependent directly upon 

 a lowering of temperature. 



The same technic was employed with several salt solutions 

 (Tyrode's, 1 Ringer's and the 0.9 per cent, "normal"), with essen- 

 tially the same results. These solutions differ from the gelatine 

 mixture in their effects upon the corpuscles apparently only in 

 that they permit crenation to occur more rapidly and more 

 extensively, and in degrees in the order named. The fact that 

 rouleaux form only in the gelatin solution indicates a closer 

 intrinsic similarity to blood plasma than any of the salt solutions 

 possess. 



Cup forms appear most abundantly in ordinary preparations 

 with Ringer's solution when the cover glass is supported by a hair. 

 The explanation that immediately suggests itself is that the float- 

 ing discs become altered into cups through adjustment to the 

 narrow confines between slide and cover glass. In other words, 

 a cup form is conceived of as a circular biconcave disc which has 

 become pushed out on one or the other of its concave surfaces. 



If the above-mentioned solutions, used in the manner de- 

 scribed, reproduce sufficiently closely the conditions which obtain 

 within the blood vessels of a living animal, the conclusion is 

 inescapable that the normal original adult shape of the red blood 

 corpuscle is that of a circular biconcave disc as was originally 

 taught. The only conceivable other theoretically more favorable 

 condition is that presented in the mesentery of a living animal; 

 but observations cannot be made without the use of an oil immer- 

 sion lens, and this involves pressure, which is believed to be the 

 chief factor in the production of cup forms through narrowing 

 the confines to which the delicate discs are compelled to adjust 

 themselves. 



1 Pfliiger's Archiv, vol. 148, p. 273, 1912. 



