September 15, 1916] 



SCIENCE 



393 



cup shape, have heated unduly their slides and 

 covers in overzealous attempts to maintain 

 normal ( ! ) conditions ? 



Experimentation in which various " physio- 

 logical solutions " are used for the dilution of 

 blood may ever, though perhaps unjustly, be 

 subjected to criticism. At best these are arti- 

 ficial media, the tonicity and colloidal consti- 

 tution of which may or may not simulate 

 blood plasma. 



To preclude such criticism natural serum 

 must be used. Accordingly, I had 20 c.c. of 

 blood drawn from my basilic vein. This was 

 defibrinated by whipping and centrifuged 

 quickly; thus an examining medium was ob- 

 tained, identical with blood plasma except for 

 the loss of one of its minor protein constituents 

 — fibrin. 



By utilizing an electrically heated warm- 

 stage, hollow-centered life slides, cover glasses, 

 as well as the air of the cell itself, may be 

 maintained constantly at body temperature. A 

 drop of serum was placed on a finger, previ- 

 ously cleaned with alcohol, and the finger 

 pricked through the drop. The droplet of 

 blood, thus diluted, was touched to a cover and 

 suspended, as a hanging drop in the life cell. 

 Vaseline served to seal the cell, the air in 

 which could be kept saturated with moisture 

 by introducing previously a drop of water and 

 sealing. A few seconds only are required to 

 make such preparations; if a large drop of 

 serum be used the loss by evaporation prior to 

 sealing is inconsiderable, whereas further evap- 

 oration in the cell can not occur. 



A microscopic examination of blood pre- 

 pared according to this technique reveals nu- 

 merous isolated corpuscles. A favorable place 

 for scrutiny is near the center of the drop. 

 Here sinking corpuscles revolve slowly, show- 

 ing alternately their concave faces. Usually 

 a few cups can be found, whereas quantities of 

 discs are seen in every field. This experiment 

 may be varied by filling shallow concave slides 

 with serum into which the drop of diluted 

 blood is introduced. Evaporation is prevented 

 by sealing with a cover and vaseline. 



Human sera, kindly furnished by three of 

 my colleagues, gave results identical with 



those already described, both when corpuscles 

 were examined in their own serum and in 

 each of the other sera. Similar tests have 

 also been made with .85 per cent, and .9 per 

 cent, saline, and with Tyrode's solution. 

 More cogent proof concerning the primary 

 shape of the mammalian erythrocyte, to be 

 derived from the study of drawn blood, I can 

 not imagine. 



Various dilutions of human serum with dis- 

 tilled water were next prepared. When a 

 droplet of blood is mixed with a drop of di- 

 luted serum containing ca. 40 per cent, water 

 and examined as before, typical cups are 

 found almost exclusively; in dilutions con- 

 taining ca. 65 per cent, water deeply dimpled 

 spheroids appear; perfect spheres result when 

 the water content is ca. 70 per cent. In con- 

 centrated serum erythrocytes crenate. It is 

 evident, therefore, that the shape of a cor- 

 puscle is, at least in part, a function of the 

 concentration, i. e., the osmotic pressure, of 

 its medium. In progressively hypotonic solu- 

 tions corpuscles imbibe increasing amounts of 

 water, ultimately becoming spheres and lak- 

 ing. In hypertonic media, water is given up 

 and crenation results. It is interesting to note 

 that between wide limits these form changes 

 are repeatedly reversible — for example, cre- 

 nated corpuscles may be restored to the disc- 

 or cup-shape and then recrenated. 



The importance of these dilution phenom- 

 ena on the question of the normal shape of 

 erythrocytes seems to me paramount. Since 

 the form of a corpuscle depends on the concen- 

 tration of its medium, how can the cup-shape 

 be normal when human serum must be diluted 

 one third to produce this type? 



Experimentation with the serum of cats and 

 dogs has given comparable results, both with 

 their own and with human corpuscles. The 

 rat, guinea-pig and rabbit have afforded vari- 

 able pictures, which I believe indicate that the 

 rodent's blood plasma may possess individual 

 variability in its tonicity, thereby rendering 

 this group of animals unfitted for experimen- 

 tation of this kind. 9 



» Details will be given in a later contribution 

 of which present paper constitutes a preliminary 

 note. 



