Phylum VII 



Nemathelminthes, Class Nematoda 



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RECOVERING INFECTIVE NEMATODE LARVAE FROM 



CULTURES 



G. F. White, U. S. Bureau of Entomology and Plant Quarantine 



THE method outlined here for recovering infective nematode larvae 

 from cultures makes use of the often-observed fact that toward the 

 close of their free-living period the larvae migrate from the medium in 

 which they have been growing. The simple apparatus used traps the 



migrating larvae in 

 water (White, 1927). 

 Convenient and 

 sufficient equipment 

 consists of crystal- 

 lizing dishes 125 to 

 150 mm. in diameter, 

 watch glasses slightly 

 larger than these di- 

 mensions, petri dishes 

 100 to 125 mm., 

 test tubes 20 by 

 150 mm., filter papers 

 9 to 12 cm., a spatula 

 with a 4-inch blade, a test tube rack, a three-quart boiler with cover, 

 animal charcoal, and sterile water. Brief steaming in the covered vessel 

 suffices for the disinfection that is needed. 



The charcoal and feces with water added are mixed properly and con- 

 veniently in one of the larger watch glasses and transferred to the half 

 of a petri dish, with a moistened filter paper covering the bottom. Sterile 

 water is poured into a crystallizing dish to cover the bottom and into it is 

 placed the half petri dish containing the culture. A watch glass is used 

 as a cover, the apparatus (Fig. 45) after labeling, is placed for incubation 

 preferably where a high humidity may be maintained. 



Many of the larvae on approaching the third larval stage migrate from 

 the culture and are trapped in the water surrounding the petri dish. In 



166 



Fig. 45. — Apparatus used for culturing nema- 

 tode larvae, a, Crystallizing dish; b, Petri 

 dish with charcoal-feces mixture; c, watch-glass 

 cover. Water surrounds the petri dish equal 

 to about one half its depth. 



