A Simple Method of Obtaining Anærobiosis

are placed at the bottom of the jar, one of the usual oxygen indicators (for example, alkali^6' glucose-methylene-blue mixture) placed aloflj? with the cultures, and the jar sealed. After jj to 12 hours, according to the size of the jar an" the amount and quality of iron filings, the colour of the indicator is discharged and co1*^ plete anaerobiosis obtained. Approximately " grammes of iron filings are sufficient to product complete anaerobiosis overnight in a container about 1,000 c.cm. capacity. Smaller amounts ?i iron filings take longer time. This method of producing anaerobiosis }s J efficient. Cultures of strict anaerobes both liquid media and on surface agar can be easily obtained. Compared with parallel inoculation incubated in Mcintosh and Fildes' jar, employ ing the standard technique of producing aneero' biosis, there is no appreciable difference in cul' tures made in liquid medium, but there is * difference in the amount of growth on soli" medium. This difference is however of not an) practical importance. The test organisms use" were Clostridium tetani, CI. histolyticum an" CI. botulinum. When comparatively clean iron filings are used there is no detectable amount of hydrogen sulphide produced (using lead acetate papers as indicators). There is, as will be readily appreciated, a reduction in the tension inside the jar. This can be readily demonstrated by opening the j^r with the opening immersed in water when water to about l/5th the volume of the jar will flo^ in. This reduction in pressure has certain advantages in that, provided the seal is efficient) the atmospheric pressure will tend to keep the jar well sealed. If however it is desired to equalize the pressure, then a neutral gas (such