28 
CHARLES F. DAWSON. 
hide. This condition is succeeded by one in which they sit 
crouched in a corner of the cage, and apparently have partially 
lost the use of the hind legs. If poked with a stick or pushed 
over they are slow in regaining their former position ; their 
body rolls somewhat from side to side before its equilibrium is 
entirely established ; the hind legs remain drawn up, and if 
forcibly extended they are not-withdrawn quickly, as in health. 
The ears lie upon the shoulders ; the head is somewhat de¬ 
pressed and extended forward, and the eyes lose their wide¬ 
awake appearance. During this period the appetite 'seems lost 
and the animal rapidly emaciates. In a typical case the symp¬ 
toms in such an animal will become progressively pronounced, 
and on the fourteenth or fifteenth day the animal will be found 
down and to have entered the paralytic stage. In many cases 
all the stages are shortened to such an extent that they are not 
recognizable, and the animal dies soon after the first symptoms 
manifest themselves. In some cases, in which the various stages 
are prolonged or the symptoms are late in being manifested, the 
cause is either to be ascribed to a weak original virus, insufficient 
dose, or, in cases where the supra-cerebral method has been 
employed, to a leakage of the injected virus through the per¬ 
forated dura-mater. For these reasons care should be exercised 
in preparing the virus to obtain a milky fluid for injection. 
In the paralytic stage, the animal lies apparently, though 
not really, unconscious, at full length on its side with eyes 
partly closed and head extended backward. The breathing is 
almost imperceptible, and the whiskers move slightly with the 
respiratory movements. The limbs have the natural position. 
Occasionally convulsibns appear, which last about a minute. 
These may be artificially produced by lightly tapping the ani¬ 
mal in the flank. During the seizure, the limbs may go through 
the co-ordinative movements of locomotion. Sometimes the 
convulsions are simply tetanic in character. The head will be 
drawn still further back and masticatory movements will be 
noticed, with grinding of the teeth. Sometimes efforts at vo¬ 
calization will be made, but no sound is produced, probably be- 
