2720 Journal of Applied Microscopy 



able to the absorption of carbon dioxide. The author emphasizes, therefore, 

 the necessity of more careful determination of the gas in interpreting the meaning 

 of this test. 



Fremlin. On the cultivation of the Nitroso- Since the work of Winogradsky upon 

 Bacterium. Journal of Hygiene III, 364, ^^xe nitro-bacteria it has been taken for 

 1893. 



granted that these organisms can grow 



only in the absence of organic foods and cannot be cultivated therefore upon any 

 ordinary laboratory media. For their study it has been common to use a medium 

 made of silica, the preparation of which is extremely difficult and unsatisfactory. 

 Fremlin finds that it is possible to cultivate this organism upon gelatin and agar. 

 He isolates them by inoculating soil into a solution of ammonium sulphate, one 

 part; potassium phosphate, one part; magnesium carbonate, 10 parts; water, 

 1000 parts. In this solution the ammonium is slowly oxidized by the bacteria. 

 After growth sub-inoculations were made and carried on for five successive sub- 

 cultures. From these final cultures plates were made for the isolation of pure 

 cultures. The use of silica proving difficult, he resorted to gelatin and agar, 

 using not only the ordinary media, but also media made from sterilized soil 

 extracts and stiffened with gelatin and agar. In all these media he found the 

 organisms would grow and from them he isolated pure cultures without difficulty. 

 He concludes, therefore, that these organisms will grow in the presence of organic 

 material. He finds that in the presence of large percentages of organic material 

 their power of converting ammonia into nitrate is decreased. 



Buchner and Meisenheimer. Enzyme bei Since the discovery of Zymase by Buch- 

 Spaltpilzgahrung. Ber. Deutsch. Chem. Ges. ner it has been regarded that other 

 XXXVI, p. 634, 1903. fermentations might also be produced 



by the direct action of enzymes secreted by bacteria. The lactic and acetic 

 fermentations have been studied by the authors. Their method of isolating the 

 enzyme is as follows : They cultivate the organism (the lactic bacteria) in wort 

 and after some days growth centrifugalize. The sediment is mixed with water 

 and again centrifugalized, after which it is mixed with 20 parts of aceton. It is 

 filtered and washed on the filter with aceton and ether and then dried in a 

 vacuum. One liter of culture yields one gram of dry substance. This is mixed 

 with an equal weight of quartz sand and rubbed with a little water. This forces 

 out of the material a product which has the property of forming lactic acid from 

 sugars even under aseptic conditions. h. w. c. 



