14 CALIFORNIA ACADEMY OF SCIENCES. [3D Ser., 



elements, equal in importance to the erythrocytes and leuco- 

 cytes. 



V. The Fusiform Elements. 



I believe that A. B. MacCallum was the first one to deter- 

 mine satisfactorily that the fusiform elements, or corpuscles, 

 in the blood of batrachians (Necturus) derive their origin di- 

 rectly from the red blood corpuscles; that they constitute, in 

 fact, what remains of the nucleated erythrocyte after the cell 

 wall, haemoglobin, and possibly part of the cytoplasm, have 

 been destroyed or separated. As regards the blood of Ba- 

 trachoseps, this origin of the fusiform corpuscle is so appar- 

 ent that few if any comments are necessary. On my slides I 

 have frequently found nucleated cells that have been injured 

 by pressure, or in which, for some other cause, the cyto- 

 plasmic membrane had been ruptured, thus allowing all of 

 the haemoglobin to escape. Such corpuscles showed the 

 faintly staining cell membrane, with here and there tiny 

 specks of cytoplasm around the edges ; but the nucleus with 

 surrounding cytoplasm was always stained, and in other ways 

 exactly resembled the free fusiform corpuscles. In the yet 

 enclosed fusiform corpuscles I frequently found the same 

 spheres, and the same structure generally, as is seen in the 

 free fusiform elements, with the exception that the nucleus 

 was properly preserved, while that of the latter corpuscle 

 was always in decay; but even in perfect and nucleated 

 erythrocytes, stained with metanil yellow and thionin, I 

 found now and then the cytoplasmic layers brought out in 

 exactly the same way as in the fusiform corpuscles, which 

 leaves no doubt as to the correctness of MacCallum's ob- 

 servations. A further proof is that if a drop of Batrachoseps 

 blood be mixed with a drop of 0.6 salt solution and observed 

 in a moist chamber, we will soon find that the erythrocyte 

 loses • its haemoglobin, the cell membrane collapses, and 

 the nucleus with adhering cytoplasm is set free. These re- 

 mains of the erythrocytes closely resemble the fusiform 

 corpuscles, or at least some of them, as it is evident that 



