Zool.— Vol. I.] EISEN—PLASMOCYTES. 9 



are various kinds, the ordinary ones, eosinophile cells, and 

 other strongly granulated cells which do not stain with any 

 of the stains I have so far tried. While it is the fusiform 

 elements and the plasmocytes which will principally occupy 

 our attention, a short description of all the elements is nec- 

 essary. The measurements given later have been calcu- 

 lated by Mr. George Otis Mitchell, whose careful meas- 

 urements of the human blood cells are well known and 

 accepted as standard. 



Non-nucleated Erythrocytes. — These constitute by far the 

 great majority of the red blood cells. The proportion be- 

 tween the non-nucleated and the nucleated red blood cells 

 is probably as 99 to 1 at any time, though I have not 

 made a sufficient number of countings to fully ascertain the 

 fact. In some Batrachoseps, especially early in the spring 

 of the year, the nucleated red cells are so scarce that 

 on a well spread cover glass I have found but a single cor- 

 puscle. At other times they are much more numerous, so 

 that in a field viewed under Zeiss A A we may count from 

 100 to 200 nucleated red blood cells, all the others being 

 non-nucleated. A striking characteristic of all the red blood 

 cells, nucleated and non-nucleated, is their great variation 

 in size. Some are smaller than the human red blood cell, 

 while others surpass it with a diameter seven times as great 

 in every direction; and this variation in size is not confined 

 alone to the non-nucleated red blood cells, but also to the 

 nucleated ones. The smallest nucleated cells besides the 

 nucleus consist of only a very narrow rim of cytoplasm 

 and haemoglobin. In the non-nucleated red blood cells I 

 have never observed any structure that I could at all iden- 

 tify as cytoplasm and centrosomes. 



Figs. 1, 2, 3, 4, 5, and 6 represent various non-nucleated 

 cells. There are also numerous cells of the same size and 

 shape as those represented in figs. 7 to n. The form 

 of the red cells varies considerably, hardly any two being 

 exactly alike; some are round, others oval, while many are 

 oblong and biconcave (fig. 5). 



Nucleated Erythrocytes. — To the description already given 



