E. E. Atkin and A. Bacot 
513 
when the larva died. This result has followed in a number of instances when the 
sterile conditions in which larvae have been living for a long period are broken 
down. In some instances no doubt this has been due to the violent character of 
the growth, with which two or three small larvae are quite unable to cope, but, 
apart from this, it would seem that some adjustment to the sterile conditions has 
occurred which cannot easily be reversed. In contrast to this, is the fact that 
larvae which are only starved by keeping them short of food in an unsterilized 
condition, are quite able to take advantage of an influx of bacteria, rapid develop¬ 
ment following immediately. 
Experiment XV. 
Development of larvae on a diet of Staphylococcus aureus. 
(Note also tube No. 7, Experiment IX.) 
Eggs sterilized by Method b were transferred by pipette into two tubes of pep¬ 
tone broth. One tube was inoculated from a B. coli culture, the other from one of 
S. aureus. 
Growth of the bacteria followed immediately in the aureus tube and the eggs 
hatched within a few hours of inoculation. 
In the B. coli tube the inoculation failed; only 1 egg hatched, and the larvae 
died within 3 days. On the 4th day the tube was again inoculated from the same 
culture of B. coli; by the following morning it was observed that the second inocu¬ 
lation had been effective and that the eggs had hatched. 
The larvae in both tubes grew rapidly and produced adults within 8 to 15 days. 
Experiment XVI. 
Question of the necessity of solid particles with the food, also note 
respecting the effect of past bacterial action on the eggs. 
It was suggested by one of our colleagues that the mosquito larvae might be 
unable to obtain nourisi.inent in a pure fluid, particulate matter being essential to 
their digestive processes. We therefore tried the effect of adding animal charcoal 
to some tubes and not to others. Eggs that had been kept moist from laying were 
used and sterilized by Method b. The theory here was to allow of bacterial action 
on the outer surface of the eggs up to the moment of their sterilization. Apparently, 
on the showing of this one test, the theory has some basis as the result showed more 
eggs hatching under sterile conditions than usual. 
The eggs were transferred to tubes of peptone water, peptone broth, pure beef 
broth, 2 % and 3 % solutions of an autolyzed extract of brewers’ yeast in distilled 
water. To the yeast extract tubes a small quantity of animal charcoal was added 
prior to their sterilization. 
Eggs hatched in some of the tubes within an hour and many more within two 
hours; such rapidity suggests past rather than present bacterial action, as even if 
the tubes were infected at the placing of the eggs in them, there was little time for 
growth, whereas all the experiments suggest that it is the vigorous bacterial action 
of a maximum infection which counts in causing hatching. 
