452 BACTERIA IN DIPHTHERIA. 
‘The only species of bacteria which we have found constantly in the 
cases of diphtheria has been the Léffler bacillus. Two other species have 
been present in many cases, viz., the well-known streptococcus, which grows 
in much smaller colonies and less rapidly than the Léffler bacillus, and a 
short, oval, often slightly pointed bacillus, growing in long chains running 
parallel to each other. ‘There are often marked irregularities in shape and 
especially in size of this bacillus, even of individuals in the same chain. 
The colonies of this bacillus are grayish-white, moist, larger than those of 
the streptococcus, but smaller than those of the Loffler bacillus.” 
THIRD. As shown by Liffler’s earlier researches, pure cultures 
of this bacillus induce characteristic diphtheritic inflammation 
when inoculated into the mucous membranes of certain lower ani- 
mals. Roux and Yersin have also shown that local paralysis is 
likely to occur in inoculated animals, as is the case in diphtheria in 
man. In speaking of their inoculations into the trachea in rabbits 
these investigators say : 
“‘The affection which is thus induced in the rabbit resembles croup in 
man. The difficulty which the animal experiences in breathing; the noise 
made by the air in passing through the obstructed trachea: the aspect of the 
trachea, which is congested and covered with false membranes; the cedema- 
tous swelling of the tissues and glands of the neck, make the resemblance 
absolutely remarkable.” 
Welch and Abbott give the following account of the results of 
inoculations into the trachea in kittens : 
‘‘A half-grown kitten is inoculated into the trachea with one platinum 
loop from a pure culture of the Loffler bacillus on glycerin-agar, eleven days 
old, derived from Case IV. For the inoculation a small median incision was 
made over the trachea, in which a hole just large enough to admit the plati- 
num loop was made. Theculture was rubbed over the mucosa of the trachea 
for an extent about three centimetresin length, and in this process sufficient 
force was used to abrade the mucous membrane. On the day following the 
inoculation no special alteration in the animal was observed, but on the 
morning of the second day it was found very weak. In the course of this 
day it became so weak as to lie completely motionless, apparently uncon- 
scious, with very feeble, shallow respiration ; several times it was thought to 
be dead, but on careful examination proved still to be breathing feebly. It 
was found dead on the morning of the third day. At the autopsy the wound 
was found gaping and covered with a grayish, adherent, necrotic, distinctly 
diphtheritic layer. For a considerable distance around the wound the sub- 
cutaneous tissues were very cedematous, the oedema extending from the 
lower jaw down over the sternum, and to the sides of the neck, and along 
the anterior extremities. Thelymphatic glands at the angle of the jaw were 
markedly swollen and reddened. The mucous membrane of the trachea, 
beginning at the larynx and extending down for six centimetres, was covered 
with a tolerably firm, grayish-white, loosely attached pseudo-membrane, in 
all respects identical with the croupous membranes observed in the same 
situation in cases of human diphtheria.” 
