No. 3-] BLOOD-PLATES OF THE HUMAN BLOOD. 637 



The second method consists in a double staining of eosin 

 and hasmalum. Stain with eosin for five minutes, then wash 

 with water for several minutes, or until no diffuse red stain is 

 visible in the serum-film outside of the red blood-cells. The 

 latter must stand out sharply. Counter stain with a strong 

 undiluted hsemalum for from ten minutes to one-half hour. 

 Wash with distilled water, and mount in thus-xylol. The 

 advantage of this method is that the filaments of the blood- 

 plates are intensely stained red, and can be followed with great 

 facility. The toluidine method stains the filaments less dis- 

 tinctly. The disadvantage of the double staining consists in 

 less differentiation of the inner spheres, as well as in a more 

 or less intense staining of degenerating and broken red cells 

 and other fragments and debris. I have found hsemalum much 

 superior to any of the other hasmatoxylin compounds, in fact 

 the only one which will stain the inner sphere and centro- 

 somes. 



The preparations were all studied with a Zeiss Apochromat 

 3 mm.. Aperture 1:40, Ocs. 8 and 12; and with an Abbe 

 achromatic oil immersion substage condenser. The latter is 

 indispensable in order to get a view of the finer details of the 

 blood-plates. In addition I consider it indispensable to use the 

 achromatic light filter, as without it the light will be neither 

 sufficiently pure nor steady enough to differentiate the inner 

 structures of the blood-plates.^ 



III. Historical Notes on the Nature of the Blood- 

 Plates. 



A complete history of the discovery of the blood-plates, and 

 of the various and contradictory views held by investigators in 

 regard to the origin and nature of these bodies, lies outside the 

 scope of this paper, and a few remarks must suffice. 



As is well known, the blood-plates in the human blood were 

 first discovered, or at least first described, by Max Schultze, 

 in 1865. He described the outward appearance of the blood- 



' See Zeitschrift f. wiss. Alikroskopie u. /. mikroskopische Technik, Bd. xiv, 



1897, pp. 444-447- 



