E. E. Atkin and A. Bacot 
511 
24th day: 
Tap water. The eggs lay dormant in this tube for 24 days; 1 c.c. of an auto- 
lyzed extract of brewers’ yeast was added (about 20%); the eggs hatched within 
15 minutes; the larvae, however, died. 
Quantities, up to aboui 10 %, of this sterile extract were added to the sterile 
tubes of peptone water and peptone broth in which unhatched eggs were lying, 
but no further larvae emerged, and the larvae which had already hatched in these 
tubes did not respond by growing. 
28th day: 
Peptone water tuhe (in which the eggs hatched on the 22nd day following an 
inoculation with a living yeast). The larvae showed slow and varied growth; 
they eventually died without pupating—the growth of yeast in the tube being 
presumably too feeble to supply sufficient nutrition. 
The larvae in the sterile tube of peptone water to which sterile yeast extract 
had been added, lived on for a long while, making little or no progress. A number 
were still living 95 days after the start of the experiment, and one lingered on until 
the 113th day, when it was still in its second instar. 
Beef broth. The larvae in the sterile tube progressed very slowly, sterility being 
maintained as shown by the sub-culture tests made at intervals. After 50 days 
a few adults were reared; these emerged at intervals over a period of 10 or 12 days, 
one, which fell into the broth and was drowned, was transferred with a platinum 
loop to a tube of sterile broth, but no growth ensued. A living specimen was fed 
on a carefully cleansed patch of skin on the arm, producing the same quickty 
passing reaction mark as do normally bred S. fasciata when they bite this individual. 
This observation suggests that Schaudin’s opinion that the reaction following the 
bite of the mosquito is due to a ferment is possibly incorrect. An attempt to feed 
another specimen, reared subsequently under sterile conditions, on the arm of a 
lady, who showed a very marked reaction to the bites of S. fasciata, failed as the 
insect died without biting, although tested on several successive days. 
Result of test carried out on larvae taken from Tuhe No. 1 
peptone broth on the \f>th day. 
Two larvae were withdrawn by Pasteur pipette on the 15th day from one of the 
peptone broth tubes which had remained sterile. 
One of these larvae was transferred to a tube of broth made from dried and 
powdered insects (mostly house flies), the other to a tube of water, in which horse 
dung had been steeped. Both these tubes had been autoclaved. The plan was to 
test if a change of diet under sterile conditions would affect growth. The larvae 
at first made no progress, but after 48 hours they began to show signs of slow growth, 
which continued for 30 to 40 days, by which time the larvae were httle more than 
half grown. They then marked time during a period of 10 or 12 days and died 
without making any further progress. 
Experiment XII. 
This test was carried out with a view to deciding if sterilized media of a kind 
more likely to be encountered in nature than those prepared for bacteriological 
experiments would allow of the larvae developing. 
