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APPLIED BACTERIOLOGY 



Water.' The most satisfactory method is a modification of 

 the Esmarch roll culture, devised by Hesse. 



Hesse's Method. — The apparatus consists essentially of a 

 glass cylinder about 70 centimetres long and 3'5 centimetres 

 in diameter ; this tube is covered at one end by two rubber 

 caps, the inner one having a hole in its centre 10 mm. in 

 diameter, and at the other end a rubber cork fits in the 



Fig. 38.— Hesse's Appakatus. 



cylinder ; through this cork a glass tube 100 mm. in 

 diameter passes, which is plugged with cotton-wool. The 

 cyhnder is sterilised by placing for one hour in the steam- 

 steriliser. The apparatus is then prepared as follows : The 

 rubber stopper is carefully removed, and 50 c.c. of sterile 

 nutrient gelatine in a fluid condition is introduced into 

 the tube and rolled out on the sides as in the preparation of 



