406 BACTERIA IN CROUPOUS PNEUMONIA. 
Kruse and Pansini (1892) have published an elaborate paper giv- 
ing an account of their researches relating to “diplococcus pneumo- 
nix” and allied streptococci. We give below a summary statement 
of their results: 
Many varieties were obtained by the observers named in their cultures 
from various sources—from the lungs of individuals dead from pneumonia, 
from pleuritic exudate, from pneumonic sputa, from bronchitic sputa, from 
the saliva of healthy persons, from the secretion in a case of subacute nasal 
catarrh, from the urine of a patient with nephritis. 
Pure cultures were obtained by the use of agar plates or by inoculations 
into rabbits. In all about thirty varieties were obtained and cultivated 
through many successive generations. As a rule, the different varieties, 
which at first were seen to have the form of diplococci, when cultivated for 
a length of time in artificial media presented the form of streptococci ; and 
the elements which at first were lancet-shaped showed a tendency to become 
spherical. 
‘ The more virulent varieties usually presented the form of diplococci 
with lancet-shaped elements, or of short chains. A variety which formed 
long chains could be pronounced, in advance of the experiments on animals, 
to possess comparatively little virulence. When by inoculations in animals 
the virulence of such a variety was restored, the tendency to form chains 
was less pronounced. 
Although, as a rule, no development occurs at 20° C., certain varieties 
were obtained which, after long cultivation in artificial media, showed a de- 
cided growth at 18° C. 
Decided differences were shown by the cultures from various sources as 
regards their growth in milk. Out of eighty-four cultures from various 
sources eleven did not produce coagulation. As arule, cultures which caused 
coagulation of milk were virulent for rabbits, and when such cultures lost 
their virulence they usually lost at the same time the power of coagulating 
milk. Virulent cultures die out sooner than those which have become at- 
tenuated by continuous cultivation in artificial media; the first, on the sur- 
face of agar, usually fail to grow at the end of a week, while the attenuated 
cultures may survive for three weeks or more, 
Pathogenesis.—This micrococcus is very pathogenic for mice and 
for rabbits, less so for guinea-pigs. The injection of a minute quan- 
tity—0.2 cubic centimetre or less—of a virulent culture beneath the 
skin of a rabbit or a mouse usually results in the death of the animal 
in from twenty-four to forty-eight hours. The following is from the 
writer’s first published paper (1881), and refers to the pathological 
appearances in rabbits : 
‘The course of the disease and the post-mortem appearances indicate that 
it is a form of septicemia. Immediately after the injection there is a rise of 
temperature, which in a few hours may reach 2° to 3° C. (8.6° to 5.4° F.); 
the temperature subsequently falls, and shortly before death is often several 
degrees below the normal. There is loss of appetite and marked debility 
after twenty-four hours, and the animal commouly dies during the second 
night or early in the morning of the second day after the injection. Death 
occurs still more quickly when the blood from a rabbit recently dead is in- 
jected. Not infrequently convulsions immediately precede death. 
‘‘The most marked pathological appearance is a diffuse inflammatory 
cedema or cellulitis, extending in all directions from the point of injection, 
