646 



SCIENCE 



[N. S. Vol. XL. No. 1035 



film. The preparation is then mounted in a 

 glass moist chamber, open to the air at one 

 end, and examined at ordinary room tempera- 

 ture. A drop of untreated human blood 

 mounted in a moist chamber serves equally 

 well, if the corpuscles be more or less separated, 

 by spreading the blood into a thin film on 

 the cover-slip. 



The preparations were studied at room tem- 

 perature by means of both natural and arti- 

 ficial light. A frosted Mazda light globe of 

 sixty watts was used as the source of illu- 

 mination, the light being passed through a 

 glass container containing sufficient copper 

 chloride to impart a weak blue color to the 

 solution. The following observations were 

 made with an ordinary Leitz 1 : 12 oil immer- 

 sion lens and a No. 4 ocular. Certain finer 

 details of structure were better revealed by a 

 No. 12 compensating ocular. 



The microdissection technique used is the 

 same as that employed by Kite^ and involves 

 the use of the Barbour pipette holder, the 

 Barbour moist chamber, and exceedingly fine 

 (1-2 microns) hard Jena glass needles and 

 pipettes. 



When blood is prepared as above described 

 certain of the cells are seen to have undergone 

 more or less pronounced crenation as soon as 

 they can be examined. If now a very fine 

 needle point be brought up under a crenated 

 erythrocj^e, then carefully elevated so as to 

 just touch the cell, and then immediately 

 lowered, the corpuscle instantly regains an 

 optically normal appearance and retains it 

 for hours. Crenated cells thus brought back 

 to the normal have never been seen to undergo 

 subsequent crenation if left undisturbed. (It 

 should be noted that in bringing the fine point 

 of the dissecting needle into contact with the 

 cell extreme care must be taken; otherwise, 

 although the cell immediately rounds up and 

 swells, yet within 20 to 30 seconds the haemo- 

 globin dissolves out and only a so-called 

 " shadow corpuscle " remains.) 



If a fine needle be raised into a drop con- 

 taining normal red blood cells no crenation 



1 A detailed description of the method will be 

 published shortly. 



occurs when the needle pierces the meniscus 

 of the drop. If now the needle point be 

 brought up alongside the cell (not touching 

 the cell but in the same focal plane) the cor- 

 puscle immediately crenates. The amount of 

 crenation seems to be dependent somewhat on 

 the proximity of the needle to the cell. As 

 long as the needle remains in place the cre- 

 nation persists, but as soon as the needle is 

 lowered out of the focal plane of the cell the 

 corpuscle instantly goes back to the normal. 

 This experiment of crenating and uncrenating 

 a cell can be indulged in indefinitely, with 

 always the same results. 



Various methods were employed. If, for in- 

 stance, a fine microdissection needle be 

 brought up alongside a completely crenated 

 cell, and if the needle point be then carefully 

 moved against the cell, pushing in a small arc 

 of the cell substance before it, immediately 

 on lowering the needle away from the cell, the 

 corpuscle rounds up and swells. In all the 

 above-quoted and subsequent experiments cells 

 brought back from the crenated stage remained 

 intact and optically normal. In fact, such 

 cells can not be distinguished from absolutely 

 normal red-blood cells. 



Even more striking results on a somewhat 

 larger scale are obtained when, instead of a 

 needle, a very fine pipette is employed. The 

 best results are obtained with a glass pipette 

 whose lumen is not more than one micron in 

 diameter. If such a pipette be raised into a 

 field of crenated erythrocytes the instant the 

 pipette pierces the meniscus of the drop all of 

 the crenated and otherwise distorted cells in 

 the field immediately round up and retain 

 their perfectly normal, regular outline and 

 appearance so long as the pipette is allowed 

 to remain in the drop. If now the pipette be 

 lowered out of the drop, all the cells immedi- 

 ately go back to their irregular, crenated 

 shape. The cells that were originally of a 

 pointed oval shape, etc., for instance, return to 

 their oval form, and the variously crenated 

 cells return to their original stage of crenation. 



If, into a drop containing perfectly normal 

 red-blood cells, a very fine pipette is raised and 

 the experimenter exerts a very slight suction 



