APPENDIX

Methods  of Breeding Drosophila

Drosophila ampelophila has shown itself to be so
generally useful for class work in genetics and is
being so widely employed for this purpose that it
may not be out of place here to give a few directions
concerning apparatus, methods and material.

CuLTURE BoTTLES.—^l^argc-mouthed bottles of
about 500 c.c. capacity should be used. Pint milk
bottles can be purchased at reasonable rates from
wholesale dealers, and serve admirably as culture
bottles. Stoppers of raw cotton are used, which
should be tight but not packed in the mouth of the
bottle.

Temperature.—The optimum is about 25° C.
Extreme summer heat kills the flies in culture bottles
unless special precautions are taken. Cold retards
the development of the larvæ indefinitely, but the
flies themselves can withstand almost a freezing
temperature. Ordinary room temperature sufi&ces,
as a rule, but a controlled temperature of about
25° C. is better.

FooD.—Ripe fermented banana is the best food.
If raw bananas with intact skin are peeled and put
into old juice contamination is not likely to occur,
but for ordinary purposes the bananas should be

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