PI E. Atkin and A. Bacot 
i)07 
were in the second and those in the inoculated peptone water in the third instar. 
No eggs had hatched in the tubes to which acid had been added 3 days previously 
and the tubes were now inoculated from No. 1; within 18 hours all the eggs in 
them hatched. 
* Another trial was made, with dilute acid of higher concentration, in one of the 
peptone tubes (No. G) in which the eggs had now lain dormant for 8 days; the 
acid reaction after the addition being much stronger than in the original broth 
tube (No. 1). 
After 48 hours, during which period no larvae hatched, the third tube to which 
acid was added (No. 6) was inoculated from tube No. 1; by next morning (18 hours 
later) one egg had hatched, another larva emerged on the 2nd day, and 2 others 
on following days. The bacterial growth in this tube was feeble, presumably owing 
to its relatively strong acidity, while the larvae in it made very little progre.ss. 
On the I4th day of the experiment two eggs were taken by means of a Pasteur 
pipette from the remaini 'g sterile broth tube (No. 7) and transferred to a tube of 
peptone broth; they lay unhatched in the tube of peptone broth for 8 days, when 
the tube was inoculated with Staphi/lococcus aureus; within 16 hours larvae had 
emerged from both the eggs. They died, however, within 3 days, apparently 
owing to the vigour of the bacterial growth. 
On the 15th day of the experiment, the broth tube from which these eggs had 
been removed (No. 7) was inoculated with 8. aureus. The culture did not grow 
and the eggs failed to hatch. Two days later the inoculation was repeated from the 
same culture; this time with success, and the eggs which had been lying in the broth 
for 17 days hatched within 16 hours. 
On the 32nd day of the experiment 1 c.c. of sterile autolyzed extract of brewers’ 
yeast (= 17 % to 20 %) was added to the remaining tube of peptone water (No. 8) 
in which the eggs had been lying dormant for a month. The eggs hatched within 
an hour, but the larvae died within a few minutes of their emergence. 
History of the larvae in the above experiment. 
Tube No. 1; eggs hatched in response to casual infection. 
The larvae were in the fourth instar by the 7th day; 4 days later the first 
pupa was noted and 3 days later the first pair of adults emerged; 2 SS and 3 ?? 
followed within the next day or two—15 days from hatching. 
Tube No. 2 broth and No. 3 peptone eggs hatched on the 3rd day of experiment. 
The bacterial growth was more vigorous in'hihe peptone water than in the pure 
beef broth. Four days after the hatching of the eggs the larvae in tube No. 2 were 
in their second instars, while those in tube No. 3 were already in the third skin. 
This rapid progress on the part of the larvae in tube No. 3 (peptone water) did 
not continue long; the dense growth of bacteria rendered the conditions unhealth}' 
and 4 days later the larvae in tube No. 2 were ahead of those in tube No. 3, 
while the latter were beginning to die off. 
On the 11th day from the hatching of the eggs all the larvae in tube No. 3 were 
dead, while two of those in tube No. 2 had pupated. The remaining larvae were 
full fed and the broth was bright and transparent, the number of bacteria having 
been reduced to a minimum either cis a result of the larvae devouring them or 
organic matter in the broth necessary for bacterial development. 
