SHAPE OF MAMMALIAN RED BLOOD CORPUSCLE 453 



The experiments in which Weidenreich ('05 ar) added gelatine 

 to 0.85 per cent sahne solution in order to reduce the 'Molecular- 

 kraft' have been described (p. 445). Admitting the results to be 

 unsatisfactor}^ he, nevertheless, features them prominently and 

 emphasizes their significance ('05 a; '05 b). If the recommended 

 three per cent gelatin (purified and dialized) be added to 0.85 

 per cent sodium chloride, or to Tyrode's solution, a medium is 

 obtained which is a dense gel at room temperature. This obvi- 

 ously does not simulate blood plasma, but it was chosen, we are 

 told, because it is the optimum concentration and gives the best 

 results. 



When the finger is pricked through a drop of this gel and the 

 resulting mixture is^ examined in a hanging drop, abundant 

 rouleaux form, and the corpuscles commonly agglutinate into 

 amorphous masses or become distorted and tailed. Cups of 

 various shapes and som,e discs are also to be found. If the 

 foregoing experiment be duplicated, except that an assistant by 

 means of a needle mix the small droplet of issuing blood evenly 

 throughout the gelatin, the resulting preparation more closely 

 approximates the normal. Furthermore, the number of discs 

 seen is increased. The distorted, agglutinated, and ruptured 

 corpuscles in the first case are apparently referable to the resis- 

 tance of the dense gel ; the issuing blood as it breaks up into tiny 

 streamlets w^hich dart along irregular paths in the gel following 

 the line of least resistance testifies strikingly in favor of this 

 probability. 



When the 3 per cent gelatin mixture is warmed it changes to 

 the sol condition. If a small droplet of blood be drawn into a 

 drop of the gelatin solution at body temperature, care being 

 taken as before that the mixing is even, rouleaux formation 

 need hardly exist. Moreover, large numbers of typical bicon- 

 cave discs are observable in edge view^; a few cups may also be 

 found. I therefore conclude that with certain precautions this 

 experiment proves the precise converse of that which Weiden- 

 reich designed it to show. Confirmatory results are found in the 

 recent work of Jordan ('15) who decides that human red blood 



THE AMERICAN JOURNAL OF ANATOMY, VOL. 22, NO. 3 



