ETIOLOGY 17 
which are immune to natural distemper show no 
symptoms when exposed to experimental infection with 
B. bronchisepticus. (2) Dogs actively immunised to 
B. bronchisepticus are immune to natural distemper. 
(3) Dogs recovering from attacks of experimental dis- 
temper induced by this bacillus are protected on 
exposure to natural distemper. (4) The B. bronchi- 
septicus is the only culturable micro-organism present 
with uniformity and in great numbers in the tissues and . 
organs of distemper cases.” 
Granting the accuracy of these statements there ~ 
appears to be little else to prove, and the first fruits of 
the discovery were the manufacture of an anti-distemper 
vaccine and serum, which, whilst not perhaps absolutely 
infallible, have nevertheless been testified to by a number 
of veterinary surgeons, dog-breeders, and others, as of 
considerable value (see “ Notes on Prophylaxis ”). 
The first lesson learned by Ferry when he started his 
investigations was that canine distemper was a disease 
of secondary infections, and as soon as it was proved to 
his own satisfaction that he had isolated the primary 
cause, many questions concerning the symptomatology— 
which had previously vexed him sorely—were easily 
explained. He says: 
“From all textbooks and monographs on the subject, 
I was taught to look to the discharges of the eyes and 
nose for the etiology; that the disease had been pro- 
‘duced by injecting these discharges, either filtered or 
unfiltered, into healthy dogs. I was struck, however, 
very forcibly by the fact that, contrary to this, all dis- 
tempered dogs in the early stages would show some 
symptoms of an infection of the trachea and bronchi. I 
at once gave up all work on the eyes and nose, and soon 
had isolated what turned out to be the cause. As the 
organism was found in pure culture in practically every 
case in the trachea, and, in several instances, in the 
blood, it would seem as though the disease was primarily 
2 
