1924] 
Sex of Adult Cecidomyidce (Oligarces sp.) 
149 
observe copulation. It does not appear to have been entirely 
proven that the males arise from larvae that have been produced 
by paedogenesis, though most students of Miastor have ap- 
parently taken this for granted without making cultures from 
isolated larvae.” 
This latter objection has been removed by the writer, who, 
in using Miastor and Oligarces as material for experimental work, 
has, for some time, made cultures from isolated larvae, and main- 
tained them on artificial culture media. The methods, and some 
of the results of this work have been reported already. A 
suitable method of cultivation of Miastor metraloas on an ar- 
tificial culture medium was found (Harris 1923, 1, ^). This 
method was improved and simplified in later work on Oligarces 
(Harris 1923, 3). Both of these methods remove the possibility 
of contamination of the culture by other larvae than those under 
observation. The data contained in this report are taken 
largely from the work on Oligarces. 
Cultures of paedogenetic larvae of Oligarces, if kept in dark- 
ness at a suitable temperature, are easily maintained in Petri 
dishes in the laboratory, on the following culture medium; 0.5 
per cent malt extract, 2 per cent agar agar, 97.5 per cent water. 
Thus the difficulty of making cultures from isolated larvae is 
greatly lessened. It may be said, however, that in making cul- 
tures from isolated paedogenetic larvae it is advisable to take a 
mother larva containing nearly full term embryos, as cultures 
made from an individual larva are more liable to be unsuccessful 
than those in which several larvae are present. By using a 
mother larva containing embryos about to be born, one is 
assured of starting a culture from an isolated larva, while, at 
the same time, providing the new colony, almost immediately, 
with several young larvae with which to carry on the strain. 
Similar results may be obtained by freeing full term embryos 
from the skin of the mother larva by dissection in water on a 
microscope slide, and then transferring these young of an isolated 
mother to a new culture. Both of the foregoing methods are 
recommended as time-saving, and as productive of well es- 
tablished colonies. 
