x, B, 2 Barber and Jones: Coccobacillus acridiorum d’Herelle 165 
given a larger and another set a smaller dose. This gave us 
some criterion of the amount and character of dosage to use. 
In each of the three series of insects inoculated there were lots 
in which some or all of the locusts inoculated with moderate 
doses died within from six to eight hours after inoculation; so 
that we had apparently reached the degree of virulence required 
by the directions. 
In each of the three series the starting culture was that 
received from the original source. In order to make sure that 
the culture which passed through a series was the same as that 
used in starting, a careful comparison was made of the culture 
obtained from insects at the end of the 12x series with that used 
at the beginning. Both were found to have the same appearance 
and motility in hanging drop, and both were Gram-negative and 
exhibited the same morphology in stained specimens. Both 
showed the same rapid growth in plain agar, and agreed in | 
showing very slight gas, with little or no acid, in lactose litmus 
agar and in lactose broth fermentation tubes. In glucose broth 
fermentation tubes both formed gas to the extent of about seven 
tenths of the volume of the closed tube, and both showed gas 
and acid in maltose litmus agar and in mannite litmus agar. 
Neither showed gas nor acid in saccharose litmus agar. It is 
possible that these sugars were not pure in every case, since 
they had been kept for some time in the tropics; but however 
that may have been, it is to the last degree unlikely that a 
contaminating organism’ would show so many characteristics 
in common with the original culture. In one of the control 
series (see below), Bacillus prodigiosus was used for a series 
‘in place of Coccobacillus acridiorum. This easily recognized 
organism was recovered from the body of an insect after the 
twelfth insect transfer. 
As controls, material was taken from the body contents of 
10 healthy locusts taken directly from the field and was spread 
on agar in test tubes. Nine of these tests showed no growth, 
while one exhibited 3 colonies, possibly contaminants. The 
method of making these cultures as well as of taking cultures 
from infected insects was as follows: The posterior leg of 
a locust was removed, preferably above the trochantofemoral 
joint. The distal part of the femur was held between the 
thumb and finger, and alcohol was dripped over it in order 
partially to sterilize the surface. After the alcohol became dry, 
the end of the femur was cut off with hot scissors, and some of 
the contents of the leg were pressed upward until they appeared 
