Gr. H. F. Nuttall 
203 
the essential changes observed consist (a) in the disappearance of the 
typical intracorpuscular pyriforms, whilst ( b ) the surviving parasites 
appear rounded or irregular prior to their disappearance from the peri¬ 
pheral circulation. In stained blood films (Giemsa) the degenerating 
parasites often show a pale, ragged or irregular appearance, and masses 
of chromatin are frequently extruded. Viewed in fresh films, the para¬ 
sites usually appear rounded. The changes undergone by P. canis, and 
this holds equally for P. bovis, consequent upon the treatment of an 
animal with trypanblue, are depicted in the accompanying diagram. 
Diagram 1, Figs. 1—4, represent normal and common types of 
parasites occurring in the blood of a dog before treatment : a rounded 
form (O), a pair of pyriforms (PP), two pairs of pyriforms (PPPP) and 
a dividing form (D). Frequent reference has been made to these types 
Diagram 1. 
Showing the degeneration of Piroplasma canis consequent upon the treatment of a dog with 
trypanblue. Figs. 1—4, normal types of parasites (see text). Figs. 5—12, parasites 
from the same dog, 6 hours after the injection of trypanblue; parasites degenerating. 
After coloured figures, from Giemsa-stained blood films, drawn with a Winkel camera 
lucida and Zeiss 2 mm. objective with eyepiece 18 ( x 3000). 
