BONE-MAKROW 223 



tion is extensive, lends weight to this hypothesis. Likewise Badertscher 

 (Amer. Jour. Anat., 15, 1, 1913) finds that eosinophil leukocytes and 

 free eosinophilic granules are very abundant in the vicinity of degenerat- 

 ing muscles in salamanders during the time when the gills atrophy, and 

 believes that the eosinophilic granules are ingested fragments of degener- 

 ated muscles and red blood-corpuscles. Eosinophils do undoubtedly in- 

 crease greatly in number during certain infectious diseases characterized 

 by extensive tissue disintegration, e.g., trirhiniasis; but disproof of intra- 

 cellular origin a teaching more in accord with our knowledge of cyto- 

 plasmic granule origin through protoplasmic activity demands direct 

 evidence of extensive granular ingestion, which is lacking. Moreover, 

 the microchemical nature of eosinophil granules differs from that of 

 hemoglobin ; also, they differentiate from basophilic granules and in 

 hemogenesis in the turtle, for example, eosinophils appear before hemo- 

 globin-containing cells are present. The free eosinophil granules in 

 degenerating tissues are more likely derived from disintegrating eosino- 

 phils, abundant in such regions. 



6. Basophil Granulocytes(J/a,s- cells) .These are identical with 

 the mast leukocytes of the blood, and possibly also with the cells of this 

 name in connective tissue, the latter perhaps representing degenerating 

 phases of the former. They are characterized by a variable polymor- 

 phous nucleus, apparent lack of centrosome, extremely slight prolifera- 

 tive capacity, and presence of spheroidal non-uniform basophilic cyto- 

 plasmic granules. They are numerically increased in marrow and the 

 circulating blood and in the spleen in certain diseases. 



7. Giant Cells or Myeloplaxes. These are relatively enormous 

 cells (of 30 to 100 microns diameter). They consist of an expansive 

 mass of homogeneous or finely granular slightly basophilic cytoplasm. 

 They may have either a single large, frequently lobulated annular, nucleus 

 (megakaryocyte) or several, even many, nuclei (polykaryocyte). Both 

 are probably derivatives of the parent lymphocyte or myeloblast. The 

 polylobular and multiple condition of the nucleus arises both through 

 mitoses (frequently multipolar) and amitoses. The polykaryocyte is 

 probably a later developmental stage of the megakaryocyte. These cells 

 are characteristic of hemopoietic foci. The polykar} T ocyte has been re- 

 garded as identical with the osteoclast. Nevertheless, their osteolytic 

 function can hardly be said to have been established ; the polykaryo- 

 cyte of the yolk-sac of the 10-millimeter pig embryo can be seen to 

 differentiate into erythrocytes, a hemoglobin-containing area developing 



about the several nuclei, the whole finally breaking up into an equal num- 

 15 



