and Laboratory Methods. 



1749 



Fig. 24. 



rods the upper and the lower metal plates are tightly 

 pressed against the bell jar, closing the apparatus 

 hermetically. On opposite sides the bell jar 

 contains small lateral tubes by means of which 

 . hydrogen is introduced and air driven out. 



Method. — Place the inoculated petri dishes upon 

 the bottom plate of the apparatus. Invert the bell 

 jar and seal the apparatus by screwing the upper 

 and lower plates firmly against the bell jar. Intro- 

 duce hydrogen at the upper lateral tube, the air will 

 escape through the other. When all the air is 

 driven out, which is determined by the hydrogen 

 tube test, seal first the exit, then the entrance of 

 gas and place the apparatus in the incubator. A 

 very satisfactory way is also to run the hydrogen 

 through continuously until the cultures are grown. 



This apparatus is also well suited for a large 

 number of tube cultures in hydrogen atmosphere. 



Novy (1893) recommends his apparatus (Fig. 

 6), designed for plate cultures in a vacuum, also for 

 plate cultures in hydrogen atmosphere. In this 

 case hydrogen is introduced at one end of the glass cock (x-y) and the air 

 escapes at the other. 



In addition he modified his apparatus for tube cultures (Fig. 14) so that 

 plates can be placed in it (see Fig. 24). Its manipulation is the same as that for 

 the tube cultures. 



Kedrowski's apparatus (Fig. 25) consists of a deep glass plate (C) with cover 

 (D). On the sides at diametrically opposite points plate and cover are perforated 

 for the entrance of gas and the exit of air. 



Method. — Into the sterile plate (C) put an open petri dish containing the in- 

 oculated medium. Coat the inside of the rim of cover (D) with vaseline. Place 

 D over C, so that the perforations in plate and cover meet perfectly. Introduce 

 hydrogen, and when the gas has replaced all the air, then turn the cover 90° and 

 put the apparatus into the incubator. 



Gabrits chew sky's plate (Fig. 26) consists of a sub-plate with a rim at its per- 

 iphery. The outer end of the rim is so constructed as to expose a 

 broad horizontal surface for the cover to rest on. This surface is perfor- 

 ated at two diametrically opposite 

 points corresponding to two 

 similar perforations in the cover. 

 Method. — Pour the inoculated 

 medium into the central part (c) 

 of the sub-plate. Cover with a 

 paraffined ground glass cover so 

 that the holes in the rim cor- 



^ 



.'i ¥, ))m\\-^')\)-)\\\\v.yi%n i 



C 



Fig. 25. 



