THE BLOOD. 183 



outside of the vessels often form abscesses, the leucocytes then 

 receive the name pus-corpuscles. The leucocytes in this condition 

 usually are dead and show signs of fatty degeneration. Frequently 

 red corpuscles follow in the wake of the white ones, passing through 

 the openings in the vessel-walls made by the former. 



In acute fevers and septic processes, as the temperature rises 

 there follows a decrease in the number of erythrocytes, with a 

 corresponding increase of leucocytes. 



Origin of Leucocytes. The source of the colorless corpuscles 

 seems to be rather extended. They originate in the bone-marrow 

 and spleen, but the credit for greatest production belongs to the 

 lymphoid tissues and lymphatic glands. From these latter sources 

 the leucocytes enter the lymph-circulation, from thence to be 

 emptied into the bloodstream. After having once gained entrance 

 to the blood-circulation there is rapid multiplication to keep up the 

 proper supply, since many succumb to the poisons secreted and 

 excreted by the various bacteria. 



One set of observers assert that all white corpuscles are derived 

 from a single type of cell; that the nongranular can form the 

 granular. Another set of observers hold that there is no relation 

 between the granular and nongranular, and that one is never trans- 

 formed into the other. 



In lymphatic leukemia the red marrow is transformed into a 

 mass of adenoid tissue, with the natural consequence that the 

 granular cells disappear almost entirely. The large clear cells with 

 a single nucleus in the marrow are the mother-cells of the granular 

 leucocytes, which, by the protoplasmic deposit of granules, become 

 granular myelocytes, in which the nuclei are still single, and are 

 largely present in myelogenous leuksemia. 



The marrow produces the granular cell, whilst the lymphatic tissue 

 generates the nongranular cell. Muir has calculated that all the 

 white cells in the blood would not suffice to form more than an 

 ounce of pus. The average life of the leucocyte is a few days. The 

 spleen is largely a place of destruction of leucocytes. 



Blood-plates, Hsematoblasts of Hayem and Haemaconien or Blood- 

 Dust. In addition to the erythrocytes and leucocytes found floating 

 in the liquor sanguinis, there have been discovered other numerous, 

 smaller bodies, termed blood-plates and elementary granules. 



The blood-plates are pale yellow or colorless discs; round, oval, 

 or crescentic in shape; and varying within wide ranges as to size, 

 being about half the size of the red corpuscle. Deetjen state 



