1288 



Journal of Applied Microscopy 



A — 



Fig. 2. (i.) Fermentation Tube. 



tation tube for bacteriologic purposes. 

 As seen from the illustration below the 

 6' tube is of smaller size, the stopper 

 with a small tube drawn out to a capillary 

 point, and a short tube used instead of 

 the flask. 



The side-tube {■ is plugged with non- 

 absorbent cotton ; the 6^ tube is filled 

 with mercury to the mark A, the cotton 

 preventing the mercury from escaping. 

 The tube B containing a convenient 

 quantity of sugar-bouillon is inoculated 

 with the organism. The rubber stopper 

 is inserted into S, the displaced air escap- 

 ing through c/. This done, the end of d 

 is sealed in the flame and the apparatus 

 placed in the incubator. The CO 2 collects in the closed end of the ?7 tube 

 under mercury, thus assuring the complete collection of the gas, which in the ordi- 

 nary fermentation tubes escapes in considerable quantities from the open end. 

 For convenience as well as for comparative study of dififerent fermenting organ- 

 isms a trench is made to hold 6 tubes (see Fig. 2-2.) Only the tubes intended 

 for the culture need be sterilized. The rubber stoppers are sterilized (in steam) 

 in a wide-mouthed bottle and kept there until used. The rubber stopper devised 

 by the writer is especially useful for this purpose inasmuch as its handling does 

 not carry with it contamination. The stopper is so made that an outer jacket is 

 formed which fits over the neck of the container, while the stopper proper is 

 within. The illustration in Fig. 2 (3) explains itself. The writer believes that 

 this form of stopper will be found useful wherever an ordinary stopper is used, as it 

 offers the additional advantage of keeping out dust and preventing the escape of 

 gas. Where the neck of the bottle is unusually thick the outer jacket is reflected 

 while the stopper is inserted. A. Robin, M. D. 



Delaware State Board of Health Laboratory, Newark, Del. 



The New Jersey State Microscopical Society. — At the February session 

 of the N. J. S. M. S., a paper on "Pebbles" was presented by Dr. A. H. Chester, 

 professor of mineralogy in Rutgers College. 



The term "pebble" was defined as a more or less rounded piece of rock 

 varying in size from that of a particle of sand to a boulder. 



The three chief agents in the formation of pebbles are the small streams and 

 rivers, the ocean and glaciers ; the last named being by far the most important 

 of the three. 



The shape of a pebble depends upon the shape of the original fragment, and 

 upon which of the three above named agents has produced it. 



A number of lantern slides were presented illustrating glaciers chiefly, and 

 their effects upon rocks. A large and exceedingly interesting collection of dif- 

 ferent sorts of pebbles was also placed on exhibition, the specimens ranging 

 from the most common forms about us to gold nuggets and diamonds, sapphires 

 and rubies in the rough — in their pebble state. 



J. A, Kelsey, Secretary. 



