CULTIVATION OF ANAEROBES 279 



upon the surface of the plates and upon the cotton plugs, thus 

 niakinp; the cull me dishes unpleasant to handle 'I'his has been 

 overcome to some extent by coveriiip; (ho jjlatcs and cotton 

 plugs with i)aper. Another source of trouble was encountered in 

 labeling the tubes with a wax pencil. The phosphorus seemed to 

 soften the wax of the ordinary red wax pencil, causing the labels 

 to become blurred. Later a blue wax ]iencil was found which was 

 not influenccHl in this way. Wo have also resortcil to the use of 

 l)ai)('r labels held in jjlacr liy ruiihcr bands, since the excessive 

 moisture in the jar will soon cause gummed labels to fall off. 



Some ililliculty was experienced in obtaining an anaerobic 

 jar large enough to hold all (he plates or cultures which we wished 

 to run at one (ime, ami at the same (ime, one which could l)e 

 easily liandlcd and remain air tight under a reduced pressure of 

 three to four inches of mercury foi' several tlays. Quart "Lightning 

 Seal" fruit jars have been used for test tube work to some extent. 

 In (his case, however, the sides of the jar and tubes must 

 be protected from the burning phosphorus. This may be 

 accomi)lished bj' strips of thin asbestos boartl. 



As a large anaerobic jar, we have used an aluminum pressure 

 food cooker (figs. 1 and 2), manufacturetl by the Pressure Cooker 

 Comi)any, of Denver, Colorado. The pressure gauge on the 

 top is removed and this opening plugged. Just before using, 

 the edge of the cover is heavily smeared with a rubber cement, 

 similar to that used on stopcocks. This jar will retain a vacuum 

 of 4 to 5 inches of mercury for as long as two weeks in the incuba- 

 tor at 37°C. (we have not tested it for longer periods.) Water is 

 placed in the bottom of the jar, cultures are placed on the wire 

 rack (fig. 2), an evaporating dish containing the phosphorus 

 is placed in the jar and covered with a bit of wire gauze having 

 a small opening in the center. This is to prevent the burning 

 phosphorus from siiattering. ^^'hen all is ready, one of the 

 stopcocks in the cover is opened and the cover is held so that it 

 may be replaced quickly A hot needle is passed through the 

 small hole in the wire gauze, and the phosphorus is ignited. 

 The cover is quickly replaced and screwed down firmly. The 

 pet cock is shut off after a few seconds, and a careful watch main- 



