1696 



Journal of Applied Microscopy 



r 



1 



Fig. 



In this apparatus two cultures may be grown simultaneously. 

 Apparatus shown in Fig. 3 works on the same principle with 

 the exception that it can take care of only one culture at a time. 

 The latter can also be used for cultures on solid media and 

 Esmarch roll cultures. 



Gruber''s Method. — Take a long test tube 'I'l 

 to 25 cm. long. About 15 cm. from the bottom 

 draw it out into a constriction as illustrated in 

 Fig. 4, plug the tube with cotton as usual, and 

 sterilize. By means of a funnel pour about 10 

 c. c. of the sterile medium and 2 c. c. of sterile 

 water into the tube and sterilize. Then inoculate 

 the medium as usual. Push the cotton plug well 

 down into the tube and insert the rubber stopper. Connect 

 the glass tube in the rubber stopper with a vacuum puihp and 

 immerse the lower part of the test tube in water at 37° C. in 

 case of bouillon or gelatin, and at 42° C. in case of agar. In 

 ten to fifteen minutes the tube is evacuated. To avoid wetting 

 of the cotton plug by the boiling and foaming medium, the con- 

 striction may be slightly and carefully flamed. While still evac- 

 uating, the tube is sealed in the flame. If agar is used, cool 

 the hermetically sealed tube in a water bath to 40° C, then roll 

 it until the medium congeals ; in case of gelatin cool slowly in 

 the air by constant rolling of the tube in the hand, so that at F'g. 4. 



room temperature the vacuum is filled with vapor. In case of bouillon cultures the 

 operation is finished as soon as the tube is sealed. 



Rotix's tube for potato cultures in vacuum is operated in 

 the same way, but the potato is introduced into the test tube 

 and the inoculation is made before the tube is constricted. 

 The same investigator also recommended for potato cultures 

 a tube as shown in Fig. 5. As 

 soon as the potato in the culture 

 is inoculated the tube is sealed at 

 <7, and the lateral tube closed with 

 a cotton plug is connected with the 

 vacuum pump. When evacuated 

 the lateral tube is sealed in the 

 flame at c. 

 Novy constructed an apparatus for plate cultures 

 in vacuum (Fig. 6). It consists of a cylinder ending 

 in a firm, broad rim. On the rim is placed a thick 

 rubber ring. The cylinder is closed by a bell jar, the 

 lower rim of which corresponds with the upper rim 

 of the cylinder. The whole apparatus terminates in a 

 stop-cock. 



Method. — Place the inoculated Petri dishes in the 



Fig. 5. 



