452 LESLIE B. AREY 



according to Weidenreich and Lewis occurs largely prior to 

 microscopic inspection, I have never seen, and, so far as I am 

 aware, no one asserts to have actually traced this transformation 

 in individually scrutinized corpuscles. With the formation of 

 rouleaux the apparent number of discs is, of course, increased, 

 for more are seen on edge. 



The factors which might be suspected as responsible for this 

 alleged alteration are decreased temperature and increased con- 

 centration of the plasma. Weidenreich, in particular, has in- 

 sisted on these factors as causing the widespread 'deception' 

 concerning the true shape of the blood corpuscle. 



The statement that the evaporation and consequent concen- 

 tration of a blood droplet, before the preparation can be made 

 and examined, is sufficient to inaugurate these modifications can 

 not be arbitrarily dismissed no matter how improbable it may seem 

 in the light of the readily observed effects of dilution and con- 

 centration upon the shape of red corpuscles ; when, however, a large 

 drop of blood is used the concentration change must be slight. 

 But that it is necessary to maintain an elevated temperature to 

 prevent rapid evaporation (Weidenreich, '02) is as astonishing 

 as a statement as it is embarrassing to defend as a doctrine 

 (cf. p. 443). 



The momentary exposure to air necessitated in making ordi- 

 nary preparations may practically be eliminated by using the 

 following procedure. Superimposed cover glasses, separated by 

 a hair, are fused at one point by heat ; if an edge be now applied 

 to a needle prick in the finger the issuing blood is drawn by capil- 

 larity between the two surfaces. Such preparations, examined 

 quickly with or without the aid of the warm stage, have never 

 jdelded evidence for the general existence of the cup shape. A 

 few cups may usually be found whereas scores of indisputable 

 discs appear. 



Since only corpuscles viewed edgewise furnish reliable data as 

 to shape, any pressure effect from the approximation of the slide 

 and cover glass in the foregoing experiments will tend to increase 

 the number of cups seen. 



