Hayem and Bizzozero have maed the presence of a third form of corpuscle in the blood. Hayem gives the name hsematoblast, and Bizzozero that of Blutplattchen to this corpuscle. Hayem's name implies the view that these form the red corpuscles, and as this view is-incorrect the name is inadmissible. We shall refer to them under the designation blood-plates. They are small colourless bodies, oval or circular in outline and disc-shaped. In cold-blooded animals there are spindle-shaped bodies which are regarded as of a similar nature. The blood-plates undergo rapid changes when once removed from the body, running together into indefinite granular masses. They may be prevented from changing if the blood be rapidly dried on a cover-glass and stained with methyl-violet (Schimmelbusch). The existence of these bodies as independent formed corpuscles is exceedingly doubtful, and their appearance is probably to be accounted for by the fact that various interferences with the blood, and especially cooling, causes a rapid deposition of solid granules having the forms described by Bizzozero.
Fig. 18. - Blood corpuscles, stained with logwood and eosine. Many red corpuscles are seen and three of the commoner forms of leucocytes: a, polymorphonuclear leucocyte; b, lymphocyte; c, large nucleated leucocyte or myelocyte.
For general work on the blood consult von Limbeck, Klin. Path, des Blutes, 1896. The recent works on the constituents of the blood are very numerous, especially since Ehrlich's publications. Ehrlich, Zeitsch. f. klin. Med., i. 1880; Charite-Annal., 1884 and 1887; Gulland, Laboratory Eep. Coll. of Phys., Edinb., iii., 1891 (literature to 1890), Jour, of Physiol., 1894; Hardy and Kanthack, Jour, of Phys., 1894; Metchnikoff, Inflammation, 1892; Sherrington, Proc. Boyal Soc, 1892; Lowit, Stud. z. Phys. u. Path, des Blutes, 1892.