108 GUIDE TO THE STUDY 



the apparatus, the funnel being held upright by ring clamps or 

 burette clamps. In Fig. 32 is shown a simplified apparatus 

 favorable for laboratory use, constructed of a 6-inch funnel, 

 3^-inch rubber tubing closed by a screw clamp, and a 33^-inch 

 sieve of 14-mesh brass screen. 



A simplified apparatus as given by Sandground, 1925, consists 

 only of a 5-inch funnel with a piece of fairly coarse cotton fabric 

 attached to the rim by paper clips. This is allowed to sag about 

 one inch into the funnel. The funnel is closed by a Hoffmann 

 clamp on a piece of rubber tubing. Water with a temperature 

 of from 104 to 108°F. is added until it covers the base of the fabric 

 and then the culture is carefully added. Within little more than 

 an hour the worms may be drawn from the funnel. 



White, 1927, describes another very convenient method of 

 isolating hookworm larvae by trapping the migrating worms. 

 Charcoal and feces are properly mixed in a large watch glass 

 and transferred to the half of a Petri dish, with moistened filter 

 paper in the bottom. Sterile water is poured into a crystallizing 

 dish sufficient to cover the bottom and into it is placed the 

 culture. A watch glass is used for a cover. Thus the larvae 

 reaching their third moulting stage, when they begin extensive 

 migration, are trapped in the water surrounding the Petri dish. 

 To collect them, the watch glass is removed and the Petri dish 

 with the culture lifted out. The water containing the larvae is 

 poured into a test-tube, the supernatant fluid is removed, and a 

 concentrate of the larvae remains. 



References 



Hegner, R. W., W. W. Cort, and F. M. Root. 1923. "Outlines of Medical 



Zoology," 480 pp. The Macmillan Company, New York. 

 Sandground, H. J., 1925. Some observations of the life-cycle, methods of 



diagnosis and incidence of Strongyloides stercoralis in the tropics. 



Fourteenth Annual Report of the United Fruit Co., Med. Dept. 

 White, G. F., 1927. A method for obtaining infective nematode larvae 



from cultures. Science, 66 (1709): 302-303. 



INTESTINAL TRICHINA 



Intestinal, sexually mature trichinae are usually recovered 

 from experimental animals 2 to 10 days after a feeding of infected 

 flesh, by slitting open the intestine and examining sections 

 microscopically with the light well cut down. If their position 

 in the mucosa is not being studied they may be recovered in 



