THE STORY OF THE RED BLOOD CORPUSCLES. 109 
‘merely a thin layer round the nucleus. The nucleus is 
round, or occasionally somewhat oval in outline, and contains 
‘such a dense network of chromatin that it stains very 
deeply. One or two nucleoli may be present within the 
nucleus. 
2. The Large Mononuclear Leuecocytes—These form only 
about 1 per cent. of the white corpuscles. They possess a 
large oval nucleus and a relatively abundant protoplasm 
without granulations. They are two or three times as large 
as the red corpuscles. In the blood they change into 
3. Transitional Forms, which have a more indented and 
more deeply staining nucleus, and a few granules in the 
protoplasm. 
4, The Polymorphonuclear Leuwcocytes—These form about 
70 per cent. of the white corpuscles. They are char- 
acterised by the presence of a multipartite nucleus which 
stains very readily. Their protoplasm has a dense granula- 
tion which stains red with eosin, but much less intensely 
than the granules of the true eosinophile cells. These 
cells are capable of active amoeboid movements, and 
possibly the form of the nucleus is associated therewith, 
for a cell with a multipartite nucleus must be able to . 
make its way through small spaces more readily than 
one with a single large round nucleus. 
5, Hosinophile Cells——These form 2 to 4 per cent. of 
the white cells. They resemble the last, with the exception 
that their granules are much coarser and stain very 
intensely with acid dyes such as eosin. 
6. The Basophile Cells (Mast Cells)—These form not 
more than } per cent. of the white cells) They have a 
nucleus which does not stain readily, and granules in their 
protoplasm which stain with basic dyes (methylene blue, 
thionin, etc.). 
7. Unuswal Forms.—Besides these varieties of leucocyte, 
all of which may be met with in normal blood, there are 
some other cells which may be discovered in some forms 
of disease. Of these the most important is a cell which 
looks like a giant white corpuscle, and which is derived 
from the marrow of the bones. It has a large faintly 
staining nucleus, and neutrophile granules in its protoplasm, 
