168 The Philippine Journal of Science 1915 
culture. The exalted dose may have been slightly larger, but 
it is not probable that this excess alone could account for the 
difference. The slow response to the inoculation in both series 
was probably due to the small size of the dose. A few locusts 
escaped from the cages, and although the dead insects were 
removed at each examination, some may have been eaten by 
others; so that the total number at the close does not reach 
quite 50. 
The white filter paper covering the bottoms of the cages 
showed few traces of diarrhoea in either, and less in the cage 
containing those inoculated with the exalted strain than in the 
other. 
Ingestion experiments were conducted in relatively small 
cages in the laboratory, in similar cages placed on the grass 
of a lawn, in corrals made of galvanized iron, and in the open 
field on a large scale. The results of the field experiments are 
given in Table II. 
By far the most attention was given to the field experiments. 
The insects here were for the most part wingless and varied 
from nymphs soon after emerging from the egg, in one series, 
to nymphs of the third to fifth instar. The greater number of 
tests were made on insects of the latter size. Automatic 
sprayers of a good type (“Autospray” No. 1, Rochester, N. Y.) 
were used, and the infective material was sprayed as early in the 
day as the insects began to feed well. The material was sprayed 
on the grass or other food in, and just in front of, the advancing 
swarm. 
Shipments were received from the laboratory daily of a num- 
ber of large bottles containing sterile broth. Usually two such 
bottles, each containing from 2.5 to 3 liters of broth, were used 
for a single spraying. Broth cultures started the day before 
were used, and never until they had become well clouded. A 
much larger amount of broth culture was used in proportion 
to the area than that recommended by the directions. 
The experiments extended over a period of more than twenty 
days, and through one period of wet weather, although for the 
most part the weather was hot and dry. The material sprayed 
consisted of cultures of 30x, 15x, 12x, and the control strains, 
Bacillus prodigiosus and Singalong. In the case of the strains 
exalted in the laboratory, 30x, 15x, and Singalong cultures 
were taken directly to the field, about half a day’s journey 
from the laboratory, immediately after the last insect transfer, 
and the stock cultures were kept in a refrigerator in the field. 
In the case of 12x, the strain exalted during the field exper- 
