Scientific Proceedings (67). 



normal body temperature was planned to compensate for the 

 cooling incident to the frequent opening of the incubator and the 

 transfer of the preparation for study to the microscope stage. 

 The microscope was used exposed to direct sunlight, and the room 

 temperature was about 73 0 F. A ring of vaseline was spread 

 around the depression in the slide, which was then filled with the 

 solution by means of the warm pipette. The finger was then 

 pricked with the needle, dipped into the stock solution in the 

 incubator, blood squeezed into the adherent drop, and the resulting 

 mixture touched to the solution on the slide. The mount was 

 quickly covered with a warm cover glass and placed under the 

 microscope for study. 



Many of the corpuscles sink at once in masses to the bottom of 

 the concavity in the slide. Those at the periphery almost in- 

 stantly form long rouleaux. Occasional complicated groups of 

 rouleaux appear. The individual corpuscles seem somewhat more 

 densely packed and more compressed than in drop preparations 

 of fresh unmixed blood. A rapid preliminary examination re- 

 vealed not a single indubitable cup-form. Careful searching may 

 discover a few cups in most preparations. Some of the peripheral 

 corpuscles crenate within the space of five minutes, and their 

 number augments for about a quarter of an hour. 



The main evidence regarding the shape of the erythroplastids 

 is derived from an examination of the more central, freely sus- 

 pended, and slowly sinking corpuscles. These are clearly circular 

 biconcave discs. They have a gently quivering motion. Seen in 

 profile they appear dumb-bell-shaped. If a freely moving cor- 

 puscle is watched for some time it may be seen to turn upward 

 now one side now the opposite side, in either case showing a 

 central depression. Viewed obliquely such a biconcave disc gives 

 the deceptive appearance of a shallow cup. This optical illusion 

 may account for a certain amount of misinterpretation. The 

 vast majority of the corpuscles remain unaltered at room tem- 

 perature during the period of observation, the space of an hour. 

 The corpuscles gradually all sink to the bottom of the preparation, 

 but remain disc-shaped, many presenting profile views. A disc 

 may be watched slowly changing into the crenated condition. 

 Placing the slide immediately after preparation on ice for a 



