456 LESLIE B. AREY 



preparation cools the cups become biconcave discs arranged in 

 rouleaux. From my personal experience I do not believe that 

 temperatures between 0°+ and 40°C. directly condition the shape 

 of the erythroplastids. Hanging drop preparations, cooled for 

 several minutes on pulverized ice, precautions being observed to 

 prevent dilution of the drop by condensation of moisture, show 

 no essential difference from those at body temperature examined 

 immediately; if retained for 10 minutes the free corpuscles are 

 also typical discs. Subnormal temperature of itself induces 

 neither crenation nor rouleaux formation. These tests merely 

 show that cooling does not modify the shape of the disc; those 

 who defend the cup shape would maintain that an almost in- 

 stantaneous change from cup to disc had already occurred while 

 the preparation was being made. 



Experimentation with other samples of human serum has been 

 possible through the kindness of three of my colleagues. ^"^ The 

 results obtained both when corpuscles were examined in their 

 own serum and in each of the other three sera were identical 

 with those already described. More cogent proof concerning 

 the primary shape of the human erythrocyte to be derived from 

 the study of drawn blood, I can not imagine. Similar extensive 

 tests have likewise been made with 0.85 per cent and 0.9 per 

 cent saline solutions and with Tyrode's solution;" the latter is 

 claimed to simulate blood plasma more closely than other phy- 

 siological solutions with the possible exception of Hogan's 

 mixture. 



It is a familiar fact that the dilution of drawn blood with 

 water causes the red corpuscles to assume a spherical shape, 

 whence they 'lake' and become colorless spheres; on the con- 

 trary media stronger than normal plasma crenate the corpuscles. 

 Various dilutions of human serum in distilled water were next 

 prepared and used as dilution media for hanging drop prepara- 

 tions. The ultimate concentration of any mixture obtained by 



10 Prof. S. W. Ranson, Mr. L. H. Kornder, and Mr. M. R. Waltz. For opera- 

 tive assistance I am indebted to Dr. Joseph Jaros. 



" For formula see Rona, P. und Neiikirch, P., 1912. Archiv f. d. gesam. 

 Physiol., Bd. 148, pp. 273-284. 



