136 
Journal of Agricultural Research 
Vol. IX, No. 5 
of lymphocytes in the blood of normal pigs, the first variety slightly 
larger than the red cells, generally spherical in shape, from 7.4 to 10 /z 
in diameter, and averaging about 8.5 /z. They have a nucleus which occu¬ 
pies nearly the whole cell, showing in most cases a crescent-shaped 
darker or lighter blue portion of the cell body at the periphery. The 
second variety includes much larger cells, 11 to 14 /z in diameter. They 
are fewer in number, have round nuclei, and occupy relatively less of 
the cell space. 
Giltner’s classification, therefore, is the same as the classification of 
large and small lymphocytes often referred to in the literature when 
discussing this particular class of cells in other animals. 
In our studies we have been able to recognize three classes of lympho¬ 
cytes. The cells of the first class are few in number and about one-half 
the size of a red cell. The nucleus is round, deeply stained, and occupies 
almost the entire cell space. These cells were observed in the blood of 
both young and older animals. The cells of the second class, the most 
numerous by far, are a little larger. They are two to three times as large 
as a red cell, the nucleus is stained dark, and a small amount of bluish 
green cytoplasm can be recognized. The cells of the third class of 
lymphocytes are still larger; they have a slightly larger nucleus and a 
larger amount of visible protoplasm. It is sometimes difficult to distin¬ 
guish between these cells and the smaller of the so-called large mono¬ 
nuclears. 
No attempt was made to work out the various percentages of these 
three classes of lymphocytes; they were, therefore, all classed as lympho¬ 
cytes. It would be extremely difficult to work out the percentages of 
these three classes, and the results would be subject to much error, owing 
to the fact that many border-line cells present themselves, and it would 
be difficult to know into just what class to place some of them. 
Targe mononuclears. —Burnett states these cells are usually about 
twice the diameter of the average red corpuscles. The nucleus usually 
occupies only about one-half of the cell and is situated on one side of the 
center. Its shape is oval or curved. Both nucleus and cell body are 
finely reticular and stain less deeply than do those of the lymphocytes. 
The cell body is faintly basophile. The cells have much the same appear¬ 
ance in the several species of domestic animals. 
Giltner 1 states that in the pig the more typical large mononuclear 
leucocytes are similar in size to the large lymphocytes and have a medium¬ 
sized nucleus, light blue and bean-shaped, and show a large portion of the 
cell body stained a different shade of blue. 
The cells which we have classified as large mononuclear leucocytes 
vary in size from a size equal to, or a little larger than, the largest lympho¬ 
cytes up to very large cells, the largest of which are 5 times as long and 5 
1 Giltner, Ward. Op. dt. 
