GENERAL PROPERTIES I THE CORPUSCLES. 407 



agglutinate into larger or smaller masses, swell, and disintegrate, 

 but if received upon a surface of agar-agar which has been made up 

 with physiological saline, together with some sodium metaphos- 

 phate (K 2 HPO 4 ), they flatten out, show a central granular portion 

 and a peripheral clear layer, and may make quite active ame- 

 boid movements. Deetjen claims also that they possess a distinct 

 nucleus. This latter statement is perhaps doubtful, as other ob- 

 servers* report that the material which stains like a nucleus is 

 present as separate granules in the interior of the plate. These 

 granules, though doubtless of nuclear material, do not have the 

 morphological appearance of a cell nucleus. It remains, therefore, 

 uncertain whether the blood plates are to be considered as inde- 

 pendent cells or as fragments of disintegrated cells. On account 

 of their tendency to agglutinate and dissolve when the blood is shed 

 it is difficult to obtain reliable data as to their numbers under 

 normal and pathological conditions. They are more numerous 

 than the leucocytes, and, according to Kemp, an average valuation 

 would be about yg- the number of the red corpuscles. Outside the 

 part that they take in the formation of thrombi and in the initia- 

 tion of coagulation, nothing is known of their function under 

 normal conditions. 



* Kemp, '-'American Journal of Physiology," 6, 11, 1902. 



