Dec. 8,1923 
Hornworm Septicemia 
481 
recently dead of the disease. None of these larvae died, indicating that 
infection in nature probably does not take place through preformed 
abrasions in the body wall. In two experiments in which 19 larvae were 
used the cages in which they were placed had been heavily contaminated 
with disease material from larvae recently dead of the disease. Of these 
worms, 2 died. 
In four cages used as controls there were 32 larvae. All of these com¬ 
pleted their feeding period without becoming diseased. Among the 
very large number of worms collected by the men at the Clarksville 
laboratory the disease was rarely encountered. In cages in which a 
large number were kept for a few days only occasionally a worm was 
found dead of the disorder. These cages, therefore, also served as 
controls. As a further control 27 larvae in five experiments were fed 
leaves which had been immersed in aqueous suspensions of decaying 
larvae that were not dead of hornworm septicemia. In this material 
many unidentified bacteria were present, most of them being probably 
of post-mortem origin. None of these control worms died of die disease. 
resistance and viability 
Bacillus spkingidis from a two-day bouillon culture is killed in a 2 
per cent aqueous solution of carbolic acid in less than one-half minute; 
in a 1.5 per cent solution, m about two and one-half minutes; m a 1 
per cent solution, in about five minutes; in a 0.75 per cent solution, in 
about one hour; in a 0.5 per cent solution, in about two hours; while 
a 0:25 per cent solution permits a feeble growth of the species. 
A three-day agar culture of Bacillus spkingidis suspended in normal 
salt solution, sealed in an ampule and immersed in a water bath, is killed 
in 10 minutes at a temperature between 53 0 and 54 0 C. Suspended in 
tap water, which is allowed to evaporate, the organisms in the film are 
dead in less than one day after becoming dry. Sterilized sand to which 
an aqueous suspension of the culture was added was found to be practi¬ 
cally sterile again after becoming dry, but the bacilli remained alive as 
long as the sand was kept moist. The latter tests, however, were con¬ 
tinued for three months only. An aqueous suspension from an agar 
culture exposed to the direct rays of the sun was destroyed in from three 
to five hours. The bacillus in a similar suspension added to sand and ex¬ 
posed to the sun was killed in less than three hours.® 
The culture remains alive on agar and in other media over long periods, 
dying out, however, when the medium becomes dry. Sealed agar cul¬ 
tures have remained alive at room temperature more than a year without 
renewal and probably will be found viable after a much longer period. 
Good growth has been obtained from four-month liquid cultures, and it is 
probable that this can be repeated from much older ones if drying of the 
media is prevented. 
A bacteriological examination of the blood of larvae just dead of the 
disease shows the presence of Bacillus spkingidis in very large numbers 
and in almost pure cultures. After a day or so following the death 
of the worms, however, the number of organisms in the remains dimin¬ 
ishes rapidly. The decaying mass contains few viable organisms by 
the time it is dry. 
1 The temperature acquired by the sand may have been a factor in the destruction of the organism in this 
instance, and the drying a decided factor. 
