32 DISEASES OF DOMESTICATED BIRDS 
The individuals in the chains occur as diplococci. No motility is 
present. 
The streptococci are stained by all of the common anilin dyes 
and are Gram positive. With Kiihn’s carbol methylene blue the 
capsules appear greenish in color. With a modification of Klett’s 
anthrax capsule stain the cocci appear dark blue while the capsules 
are pale red or pink, with dark red undulating contours. ‘The cap- 
sules are seen distinctly only in material from the animal body. 
The streptococci grown on the various culture media show them 
very poorly or not at all. 
The organism grows aerobically and anaerobically and its optimum 
growth temperature is that of the body. It thrives best on solid 
blood serum, and grows well in milk. It can also be grown on meat 
extract bouillon, gelatin, agar, agar gelatin and grows least well on po- 
tato. In order to cause rich growth an addition of 4 to 6 per cent 
of glycerin or one per cent of sugar is necessary. 
Acid is formed in saccharose bouillon and indol in limited amount. 
Gelatin is not liquefied. 
It is very sensitive to drying and also to heat. In bouillon cul- 
tures which have been warmed to 80° C., for five minutes it is killed. 
At 100° C. it is killed in 44 minute. One per cent solution of 
carbolic acid kills in 2 minutes, while a similar solution of liquor 
cresoli saponatus, lysol, and creolin renders it inactive in three 
minutes. . 
Pathogenesis. The disease is transmitted to hens by inocula- 
tion of blood or pieces of organs as well as by inoculation with cul- 
ture. Infection with the latter succeeds through subcutaneous in- 
oculation or when finely dissipated bouillon culture is inhaled. In 
eareasses of birds dead after subcutaneous inoculation, evidence of 
coagulation necrosis is seen frequently, accompanied by infiltration 
of the surrounding tissues with bloody or purulent fluid. 
The time of appearance of symptoms in hens after artificial in 
fection varies greatly. Sometimes sickness is noted after six days, 
with death occurring after seven days more. Again, it is possible 
for 30 to 70 days to elapse between the time of inoculation and death. 
The disease is transmissible by subcutaneous inoculation to pigeons, 
rabbits, white mice, gray mice, and lambs. The course of the disease 
is more acute in pigeons than in hens, but the lesions are similar. 
Dogs, ducks and guinea pigs do not succumb to artificial infec- 
tion. 
Differential diagnosis. The observation of capsules surround- 
