492 
Stegomyia fasciata 
Effect of the introduction of living yeast cells. 
Experiment XI. To a tube of peptone water in which eggs had 
been lying dormant for 15 days, about 1 in 5 of a sterile watery e:vtract 
of brewers’ yeast was added. No result followed within one week, 
when the tube was inoculated from a living yeast culture. All the 
eggs hatched within a few hours. 
Experiment XXII. Some of the eggs placed in a sterile tube of 
distilled water, with 1 in 6 of beef broth added, remained dormant for 
28 days. A small mass of cells from a culture of Saccharomyces cere- 
visiae on wort agar was added, when the dormant eggs hatched within 
a few minutes. 
In the same experiment 7 tubes of distilled water, in which the 
^ggs had lain dormant for 28 days, were subjected to the same treat¬ 
ment, most of the eggs hatched within 5 to 10 minutes. 
Experiment XXIII. Eggs that had been lying dormant for 28 days 
in a tube of sterile distilled water, containing 1 in 6 of the filtrate from 
a broth culture of B. coli, hatched within 10 minutes of the introduction 
of a small mass of living cells of brewers’ yeast. 
In the same experiment (XXIII) on the 100th day 3 % of sterile 
autolyzed yeast was added to a tube of sterile distilled water in which 
there were dormant eggs. One egg out of 9 hatched within 15 to 20 
minutes; after an hour and a half, during which period no further 
eggs hatched, a small mass of living yeast cells from a wort agar cul¬ 
ture was added, and the remaining 8 eggs hatched mthin 15 minutes. 
These examples afford clear evidence of the stimulus to hatching 
exerted by living yeast cells. In Experiment XI the yeast used was 
one that had been isolated from a human, throat, but in the other tests 
S. cerevisiae was used. 
Effect of the presence of living moulds. 
No special tests were carried out with moulds, but during the course 
of the experiments it was remarked that when a mould developed in an 
otherwise sterile tube many if not all the dormant eggs hatched. It is 
apparently possible for moulds to exert this influence when very small 
and quite inconspicuous. In a number of cases in which eggs had lain 
dormant for several days their hatching was quite inexplicable until 
a tiny white speck, which proved subsequently to be a growing mould, 
was noticed. A microscopic examination in one such instance showed 
the hyphae ramifying over the surface of the egg shells. Many ex- 
