8 CALIFORNIA ACADEMY OF SCIENCES. [3D See., 



as the one used with sections; the cover glasses are first 

 floated in one liquid, then in the other, and finally washed 

 and mounted in the usual way. By this method the centro- 

 somes in the plasmocytes will stain, but the cytoplasmic 

 sphere will remain unstained. Valuable only as showing the 

 centrosomes. 



Ehrlich-Biondi and Others. — Useful for all elements ex- 

 cept for plasmocytes. The latter are diffusely stained, 

 and the respective spheres are seldom differentiated. The 

 effect is to some degree the reverse of toluidine. The 

 hyalosphere is never left clear and is seldom differentiated 

 from the plasmosphere ; the granosphere is frequently left 

 lighter than the centrosphere; the other blood elements 

 are, however, exquisitely stained. In order to attain the 

 best results the mixture should be acidified with oxalic acid 

 and water, and even the cover glass should finally be washed 

 off with a weak solution of the same. In this way the 

 centrosomal spheres in the leucocytes are brought out 

 strongly and chromatically. 



Among other stains I found metanil yellow useful in 

 staining the plasmocytoblast while yet in the erythrocyte. 

 It will now and then, not always, bring out the outlines 

 sharply, but will only give a few details. The method is to 

 first stain for several minutes with an aqueous solution of 

 metanil yellow, wash with water, and double stain with 

 thionin. A second staining with metanil is sometimes nec- 

 essary. By this method I have demonstrated the existence 

 of the plasmocytoblast, as well as the two outer layers of 

 cytoplasm, in perfect, nucleated erythrocytes. 



IV. The Blood Elements. 



General Remarks. — The respective elements in the blood 

 of Batrachoseps are in short as follows: Nucleated erythro- 

 cytes, non-nucleated erythrocytes, polymorphous leucocytes, 

 lymphocytes with solid round nucleus, fusiform corpuscles, 

 degenerating leucocytes, and finally plasmocytes; the latter 

 now described for the first time. Of the leucocytes there 



