4 - Fibrin .—Appears as a meshwork. of very 
delicate fibrils in the thicker parts of the film. 
Abnormal Cells and Conditions 
Normoblast .—A nucleated red cell about the size 
of a normocyte (Fig. i). Two forms occur {a) young 
forms with the nucleus having its chromatin radially 
arranged ( radkern ) staining more deeply than that of 
any leucocyte and with a narrow rim of protoplasm. 
( b ) Older forms with dense nucleus and with broader 
protoplasm. The protoplasm may shew polychromasia 
(vide below) or basophilia, or both together. 
(•) 
o Miii(~ 
7n 
Fig. I 
Megaloblast .—A nucleated red cell of abnormal 
size (Fig. i). The network of the nucleus is more 
delicate and stains less deeply than that of any leucocyte. 
The protoplasm may be very polychromatic so that its 
resemblance to a leucocyte is then considerable. 
Basophilia also may be present. 
Pyknosis .—The condition of the nucleus in which 
instead of shewing a network, it appears quite structure¬ 
less and stains more deeply than usual. Probably it is 
an indication of degeneration. This condition may be 
seen in the two previous erythroblasts. 
Karyorhexis .—The condition in which the pyknotic 
nucleus of nucleated red cells has broken up into 
