Further reports (no. 3) on flies as carriers of infection.

Date:
1910
Catalogue details

Licence: Public Domain Mark

Credit: Further reports (no. 3) on flies as carriers of infection. Source: Wellcome Collection.

    7/76 page 3
    the bottom and occasional shaking prevented them from getting out. In this way a considerable number of flies could be caught in a few minutes. After a sufficient number of flies had been captured they were placed in one of the experimental cages. These consisted of cylindrical glass chimneys about three inches in diameter and nine inches in length. One end of the chimney was closed by gauze kept in place by a piece of thin paper gummed round the chimney over the gauze. The other end was open and when in use rested on a clean quarter-plate negative glass. (Plate I., Fig. 1.) Other cages of the same kind but smaller (one and a half by six inches) were also made use of. The transference of the flies from one such cage to another can be very easily accomplished. The fresh cage is placed on the bench with its open end upwards and the full cage with the negative glass still in place is placed on top of it. The negative glass is then slowly withdrawn leaving the two cages in free communication. By taking up the two cages in this position and holding the fresh one in the direction of the light most of the flies can be induced to pass into it. If any difficulty occurs they can be blown from the old cage into the other. A fresh glass plate is then inserted. between the cages. Flies have been kept alive in such cages, with daily transfers to fresh cages, for more than three weeks. It was very rare for a fly to escape or to be injured during the process of transference from cage to cage. The flies were usually fed once daily. The liquid food (syrup, milk, sputum, &c.) was deposited in separate drops on a clean negative glass, which was placed in contact with the one on which the cage stood. The cage was then slightly tilted and slipped into position over the food on the new glass. Infected food was given in the same way. In order to obtain a few flies from a cage for cultural purposes the following plan was adopted. A piece of wood about six inches square, in which a round hole, slightly larger than the diameter of a cage, had been cut, was lined with cloth so as to closely grip the sides of the cage when the latter was placed in the hole. To one edge of the cloth gauze was sewn to form a conical bag about six inches in length and about two inches in diameter at its free end which was open (Plate I. Fig. 2.). When in use the cage is slipped from the negative glass over the wooden frame, and is made to fit into the hole init. A long test tube is then inserted into the cage through the gauze bag and the required number of flies caught in it. This apparatus worked extremely well for no flies escaped or were injured, in a large number of experiments, during the manipulations. B.—ANATOMY. Note on certain points of importance in the anatomy of the alimentary canal of the fly. . The cesophagus passes from the proboscis through the cephalic ganglion and neck into the thorax. At the junction of the anterior and middle thirds of the thorax it divides. One part, the crop duct, is continued backwards into the anterior part of the abdomen and becomes expanded into the crop, and the other passes into the proventriculus which is situated immediately above the bifurcation, 16659 A
    digitised image 1
    digitised image 2
    digitised image 3