which arrest Micrococcus melitensis. According to Doerr it is transmitted hereditarily through the egg and larva of phlebotomus to the imago; this, however, has not been firmly established experimentally.
Representatives of the genus Phlebotomus are to be found in most tropical and sub-tropical countries. The various species are usually designated "sand-flies." They are exceedingly minute, very delicate, yellowish, greyish, or brownish, somewhat slenderly built insects that bite principally during the night and
Fig. 62.—Female phlebotomus. (After Alcock.)
that can pass easily through the meshes of an ordinary mosquito net. At rest the wings are uplifted. The legs are long and slender; the wings, body and antennæ are thickly covered with short hairs. The joints of the antennæ are constricted. The proboscis is as long as the head. The tips of the piercing apparatus (which in other respects resembles that of the mosquito) project beyond the labium. The leaf-shaped wings are somewhat narrow and show all three branches of the second longitudinal vein very distinctly. (Fig. 62.)
P. papatasii (the species on which Doerr's observa-
