136 APPENDIX A 



Air- 



Cotton 



E=3 EiS 





Qr*-Screw clamp 



■Air 



j^-«^Cotton 

 ,^,.,. ~ZJtr plugs 



^C.^^1> 



2-liter flask 



. l-llter 

 culture 



An incubator cabinet of moderate size, avail- 

 able from any scientific supply house, is useful 

 for the preparation of large quantities of culture 

 and is essential for the incubation of plates con- 

 taining Pneumococcus. 



b. Aeration 



An aerator assembly, leading from either a 

 compressed air line or an aquarium bubbler 

 (alternatively, suction may be used to drive the 

 aerator), composed as shown in the diagram, 

 provides for aeration of four student cultures. 



For aeration of large volumes of culture 

 (100 ml to 1000 ml), an aerator stone (available 

 from Fisher Scientific Co.) attached by gum 

 rubber tubing to a pyrex tube plugged at the 

 opposite end with cotton should be used. 



c. Ultraviolet irradiation 



A satisfactory source of ultraviolet light is a 

 General Electric 15-watt germicidal lamp in- 

 stalled in an ordinary fluorescent desk fixture. 



To avoid injury to the eyes, students should 

 wear safety glasses of either glass or plastic. 



d. Filtration 



Seitz filters and filter assembles for prepara- 

 tive sterilization of solutions containing heat- 



labile material may be purchased from any 

 scientific supply house. 



Porcelain candle filters, made by Coors, size 

 10 mm X 55 mm, porosity No. 5, for use in 

 the virus filterability experiment may be ob- 

 tained from Arthur H. Thomas Co., Philadel- 

 phia, Pa. The filters should be inserted into 

 rubber stoppers to fit into 500-ml suction flasks 

 and permanently marked for use in phage or 

 bacterial filtration. The filtration assembly 

 should look as shown in the diagram. 



Cotton 

 padding 



g^ 500-ml suction 

 "'' flask 



