1750 



Journal of Applied Microscopy 



respond with those in the cover. Introduce hydrogen and when all the air is re- 

 placed, carefully turn the cover 90 degrees, sealing hermetically. In addition 



Gabritschewsky recommends the use of an 

 alkaline solution of pyrogallol which is poured 

 into the rim before the gas is introduced. 

 Pig 20. ^^ similar plate (Fig. 27) was constructed 



by Kamen. Its method of manipulation is 



exactly the same as that of Gabritschewsky. 



In case of Beck's plate (Fig. 28) a common petri 



dish is used. It is covered with a plate carrying 



two lateral tubes for the introduction of gas and 



exit of air. The periphery of the cover is so shaped 



as to form a small reservoir which may be filled 



with water in case of cultures that require a long 



period of incubation. By means of short pieces of 



stout rubber tubing the laterals are connected with 



short constricted glass tubes which are sealed in 



the flame when the plate is oxygen free. 



Method. — Pour the inoculated medium into the 



sterile plate and put the cover in its place. When 



the medium is congealed fill the rim (X) between 



Fig. 28. 



Fig. 28. 



the plate and the cover with liquified paraffin. When this is solidified 

 the air by gas and seal the constricted tubes in the flame. 



Aren's plate (Fig. 29) consists of an ordinary petri dish carrying lateral 

 tubes which open into the interior of the plate. The space between 

 the rim of the cover and that of the plate is filled with liquified paraffin. 

 When the air is expelled by gas the laterals are sealed in the flame. 



Epstein'' s plate is a modification of that of Aren. Instead of 

 the lateral tubes of glass similar tubes of firm rubber are used. The 

 rubber tubes are a part of a solid 

 rubber band that covers the per- 

 iphery of the plate. When the 

 hydrogen has replaced the air 

 the plate is sealed by pushing 

 well fitting glass rods into the 

 lateral rubber tubes. Fig. 29. 



replace 



