486 
Stegomjia fasciata 
Preliminary Notes. 
The experiments on which this paper is based were carried out in 
intervals of time during the course of other work, which in view of the 
war was of more immediate importance, although the actual delay 
which resulted from this cause was not serious, because, owing to the 
slow growth of larvae in some experiments, and the lengthy periods 
during which eggs remained dormant in others, slow progress was 
inevitable. From another aspect, however, the length of the gaps, 
extending in some instances over several months, between an initiatory 
experiment and its repetition, exerted a considerable influence on the 
final results, introducing an element of uncertainty as to the nature of 
the cause to which divergent results were due. For instance, the 
action of killed cultures and sterile extracts on dormant eggs is not 
consistent ^in an earlier and later series of experiments) and it remains 
a matter of opinion whether the contradictory nature of the results 
arises from the treatment of the eggs, the conditions to which the 
parents were exposed, or the fluctuations in their heredity, which is 
possibly adjusted to the needs of climatic conditions in the natural 
habitat of the race of S. fasciata experimented with. 
The bacterial side of the research was greatly hampered in that one 
of us had to drop all practical help in research owing to war work at 
a distance from the Institute, and, although he continued to act in an 
advisory capacity, it was not possible in his absence to follow various 
interesting points or to determine the species of the bacteria and yeasts 
which appeared in the course of the experiments. 
It is perhaps necessary to add a word of explanation in regard to 
the use of the word “sterility.” When working with a definite species 
or group of bacteria for which the suitable conditions of temperature 
and description of media are charted, the word “sterility” has a definite¬ 
ness which hardly applies to this work. As here used the word refers 
to a failure of the organisms to make their presence apparent under 
circumstances conditioned to the needs of the mosquito larvae. Cul¬ 
tural tests for sterility were carried out with tubes of peptone broth 
and agar slopes for bacteria; • in the case of yeasts with tubes of wort 
agar. In many cases experimental tubes which repeatedly gave sterile 
results when the inoculation was performed with a platinum loop were 
proved to be infected when the test was carried out with a Pasteur 
pipette which transferred 0-25 to 0-5 c.c., showing how slight the infec¬ 
tion really was, either owing to the unsuitability of the temperature or 
