and Laboratory Methods. 



1697 



m 



cylinder, invert the bell jar over it, and close firmly by applying clamps with 

 rubber lined jaws to the union of the cylinder and bell jar. One end of the 

 turn cock (x-t) is connected with a thick-M'alled rubber tubing which is closed 

 by a screw compressor. The other end is connected with a vacuum pump and 

 when evacuation is complete the turn cock is turned and the vacuum pump is 

 disconnected. 



Zufinski m 1898 introduced a new and simple method of evacuation. It is 

 based on the principle of Toricelli's vacuum. The apparatus (Fig. 7) consists 

 of a tube which is constricted at each end, each constriction carrying a glass 

 turn cock, a long glass tube holding a column of mercury, 

 and a small beaker filled with mercury. 



Method. — Fill tube ;;/ completely with medium ; inocu- 

 late through c, connect the constriction at c' by means of 

 a piece of stout, elastic rubber tubing with glass rod g. 

 Close both turn cocks. Reverse the whole apparatus, fill 

 the glass tube g with mercury ; close the end with the 

 finger and return the apparatus to its original position, Fig. 

 7, standing the open end of the glass tube ^ in a beaker 

 b containing mercury. Tjie column of mercury falls to 

 750 mm., and above it there is an absolute vacuum, the 

 Toricellian vacuum. Now open cock c\ instantly the 

 medium descends and above it there is formed an absolute 

 vacuum. Close cock c' and paraffin it. Remove glass 

 tube g and put the apparatus into the incubator. The 

 diameter and length of glass tube g govern the capacity 

 of the vacuum. The gases produced by bacterial activity 

 can evolve without endangering the apparatus and can be 

 examined without interference by other gases. 



For the above method any flask or test tube may be 

 used. When filled with inoculated medium it is closed with 

 an air tight, mono-perforated rubber stopper. The perfo- 

 ration carries a snugly fitting glass tube which is connected 

 with a long, heavy glass tube by means of a short piece of 

 rubber tubing, carrying a firm clamp, which serves in the 

 place of the glass turn cock. The manipulation is the same 

 as with the previous apparatus. 



While the few devices and methods described in this 

 category appear to be the only ones specially designed for 

 vacuum cultures, there exist a large number of apparatus 

 which may be and have been used for this purpose. Thus 

 most of the devices invented for anaerobic cultures in an atmosphere of inert 

 gases may easily be adapted for vacuum cultures. For their description the 

 reader is referred to their respective classes. Otto F. Hunziker. 



New York State Veterinary College, Cornell University. 



1. I wish to express my appreciation to Dr. V. A. Moore and Dr. E. M. Chamot for valu- 

 able suggestions in this work. 



2. The entire bibliography will appear at the end of this series. 



/ 



Fig. 7. 



