Zool.— Vol. I.] EISEN— PLASMOCYTES. 5 



of cytoplasm; and that the plasmocytes have thus become 

 free and independent elements of the blood. So far I have 

 only demonstrated the presence of the plasmocytes in 

 Batrachoseps, Phrynosoma, Diemyctylus, and human blood, 

 and it is not improbable that with proper methods they 

 will be found in the blood of other animals. This paper 

 will, however, treat only of the blood of Batrachoseps; 

 but I may be permitted to state that, as regards the human 

 blood, the plasmocytes are so small that without first hav- 

 ing studied the larger ones in the Batrachoseps blood 

 I could never have recognized their structure. In the 

 human blood they have been confounded with blood plates, 

 the structure having been obscured by improper methods of 

 investigation. 



Some may, after a perusal of my plates, insist that the 

 blood of Batrachoseps is so called pathological blood, on 

 account of the abnormal form, variation in size, absence of 

 nuclei, etc. ; but I will here hasten to state that this is not 

 the case. Batrachoseps possesses the same form of blood 

 whether young or old, whether examined in the spring, 

 in fall, or in winter. In fact, the blood described here is 

 absolutely normal. 



II. Methods of Investigation. 



General Remarks. — The delicate plasmocytes can only be 

 studied on cover glass preparations, and even for the other 

 corpuscles this method of investigation was found the most 

 exact and satisfactory. Observation on moist stage and in 

 0.6 salt solution was also found useful and instructive. The 

 methods generally used for preparing cover glasses with 

 blood of higher animals are useless for batrachian blood. 

 The large corpuscles would roll up and twist, and become so 

 distorted that no minute details could be made out. I have 

 obtained the best results as follows : the covers must be ab- 

 solutely chemically clean and polished. For spreading the 

 blood I use a pair of small forceps with curved prongs of ex- 

 actly the same size and shape. The animal is etherized 



Proc. Cal. Acad. Sci., 3D Ser., Zool., Vol. I. October 20, 1896. 



