544 
Proceedings of the Royal Society of Edinburgh. [Sess. 
The animal then gradually recovers, eats well — even ravenously — and, 
although the emaciation may be arrested for a while, the original weight is 
not usually entirely recovered. After an interval extending over weeks or 
even months, during which, except for emaciation, the animal appears in 
perfect health, death suddenly takes place. 
More rarely the animal is obviously ill for two or three days before 
death, refuses food, and becomes comatose just before the end. 
Post-mortem Appearances. — Seat of Inoculation. — The site of the skin 
incision is occupied by a firm linear scar, usually adherent to the periosteum 
and bone beneath ; the disc of bone, if it has been replaced, has usually 
united completely. 
Cranial Cavity. — Slight injection of meningeal and cerebral vessels 
usually present ; brain substance appears normal. 
Cultures from brain substance and cerebro-spinal fluid yield only a 
scanty growth of M. melitensis or remain sterile. 
Thoracic Cavity. — Lungs usually anaemic ; otherwise normal. Cultures 
from heart blood remain sterile. The sedimentation value of the serum 
varies within very wide limits ; it may be as low as 1 : 20, or as high as 
1 : 10 , 000 . 
Peritoneal Cavity. — Peritoneum and intestines blanched and anaemic ; 
no subperitoneal, omental, or mesenteric fat visible. Spleen often hyper- 
trophied. Otherwise viscera normal. 
Bone Marrow. — In chronic infections the constitution of this tissue shows 
marked alterations from the normal. Nucleated red cells and lymphoid 
cells , that is, giant cells, mononuclear cells, and lymphocytes are markedly 
increased in number ; granular cells, i.e. myelocytes and polymorphonuclear 
leucocytes, are considerably diminished, the whole forming a typical lympho- 
erythroblastic bone marrow, and is in marked contrast to the leucoblastic 
marrow associated with, for instance, pneumococcic infections of these 
rodents. The following table gives counts averaged from ten intracranial 
inoculations in the guinea-pig. 
Type of Cell. 
Normal. 
M. melitensis 
Septicaemia. 
Lymplioid cells .... 
43-3 
61 T 
Granular cells ..... 
56-2 
38*4 
Nucleated red cells , 
8-0 
18-0 
Cultivations from liver usually remain sterile ; those from spleen and 
bone marrow may or may not yield a scanty growth ; on the other hand 
