1746 



Journal of Applied Microscopy 



Fig. 17. 



through the opening at (a) into the receptacle, then (a) is also 

 constricted. Having passed hydrogen through until all the air 

 has escaped, the two ends, first the exit, then the entrance, are 

 sealed in the flame. 



Roth (1893) recommended a similar device. His ap- 

 paratus is illustrated in Fig. 18. It is used for solid medium. 

 Method. — Plug both openings with absorbent cotton and 

 sterilize. The plug at (a) carries a corkscrew, that at (b) is 

 attached to a fine copper wire. Introduce about 8 c. c. of the 

 liquified medium (gelatin or agar) and sterilize on three succes- 

 sive days. For this purpose the flasks may be stood upright in 

 wire baskets. After inoculating in the usual way, let the medium congeal. Then 

 push by means of the cork screw the plug at (a) down far enough to touch the 

 medium ; introduce hydrogen at (b) by connecting (b) by means of rubber tubing 

 with a generator. The rubber tubing carries a clamp. In order to prevent the 

 mixing of air and gas as much as possible, it is best to incline the apparatus so that 

 the neck points downward. When all the air is replaced by the inert gas pour a 

 little melted paraffin on the cotton plug in the neck. When congealed dip tube 

 (b) into liquid paraffin and remove the rubber tubing. The plug in tube (b) is 

 thus saturated and the tube filled with paraffin. This paraffin seal proved very satis- 

 factory. In order to get access to the 

 grown colonies, warm the neck and pull ^^ 

 the cotton plug out by means of the 

 corkscrew. /k 



For making cultures in the field V_ 



Roth used a similar apparatus (see 

 Fig. 19). In order to avoid breakage, 

 the small tube (b), shown in Fig. 18, is discarded and the hydrogen is intro- 

 duced in the laboratory. For this purpose a small cotton plugged sterile metal 

 tube is inserted in the apparatus. When the air is all driven out, the neck is 

 filled with paraffin and the metal tube carefully removed by means of a copper 

 wire which had previously been attached to it. 



Blucher (1890) recommends the apparatus illustrated in Fig. 20. A funnel 

 shaped bell jar with a cotton plugged opening (D) and weighted down with lead 

 (F) rests in a glass bowl (A). The petri dish is kept in its place by means of a 

 spring wire ring with three projections reaching to the walls of the bowl. 



Method. — Pour the inoculated me- 

 dium into the open petri dish (B). 

 Place the bell jar over it and pour into 

 the glass bowl diluted glycerin (1 part 

 glycerin, 3 parts water) until the in- 

 terior is completely separated from the 

 exterior. Introduce hydrogen through 

 the opening at (D). The air escapes 

 through the glycerin in bubbles. 

 Fig. 19. When all the air is out, generally after 



Fig. 18. 



