and Laboratory Methods. 1673 



obtained in any other way. With this method the author has studied a long 

 series of bacteria, including coccus, bacillus, and spiral forms, spore bearers and 

 non-spore bearers. The details of this work cannot be given here, but the most 

 striking feature is the demonstration, in every species of bacteria, of a distinct 

 central body surrounded by a clearer, less staining material, on the outside of 

 which is a thin sac. The author is quite convinced that the central body is a 

 nucleus, that the surrounding material is cytoplasm, and the sac corresponds to a 

 cell wall. The evidence that the central body is a nucleus is not based wholly 

 upon its uniform presence, but also upon the fact that, when the bacteria divide, 

 the division is preceded by a lengthening and then a division of the nucleus into 

 two, one of which remains in each of the resulting cells of cell division. The 

 division of the cell is thus almost identical with the division of a typical nucleated 

 cell. The author finds, further, that when spores are formed, they are formed 

 around nuclei, so that each contains in its center one of these bodies. In the 

 fully formed spores the nuclei are no longer visible, but the study of the growth 

 of the spores demonstrates the presence in the center of a nucleus. The author, 

 in short, takes the position that a bacterium is a typical cell with the same parts 

 that are found in larger cells of higher organisms. The work is very carefully 

 done, and both the work and the figures give evidence that the author has been 

 sufficiently careful to avoid errors. This paper must be regarded as a very large 

 contribution to the theory that bacteria must be considered as typical cells. 



H. w. c. 



Hamraerl. Ein Beitrag zur Zuchtung der The author has added a few practical 

 Anseroben. Cent. f. Bac. u. Par. I, 30: suggestions tO the somewhat vexed 

 ^ ' '^°^" question as to the best methods of inves- 



tigating anaerobic bacteria. He points out that the irregularity in the results 

 obtained by different investigators is due to the uncertainty and errors of methods 

 and, in considerable degree, to the fact that the methods employed do not 

 totally eliminate oxygen. To remove these errors is the purpose of the work 

 done by the author. He uses a solution of methylene blue in the culture 

 medium, to determine whether the last traces of oxygen are removed ; for when 

 the oxygen is wholly removed the methylene blue is completely decolorized, 

 whereas, if a trace of color remains, it indicates the presence of oxygen. Various 

 methods of culture, previously used, proved by this test to be unsatisfactory. 

 The plans which he adopts himself are, essentially, as follows : He uses, as a 

 deoxidizing agent, a solution of NH^SH, prepared in a special way described 

 in the article. This material, placed in a culture medium, does not prevent the 

 bacteria growth, but absorbs every trace of oxygen, as indicated by the methylene 

 blue test. By mixing a certain amount of this material with his culture medium, 

 and then placing his Petri dishes in an atmosphere of hydrogen, or one in which 

 oxygen has been extracted, he obtains plates which contain absolutely no oxygen. 

 He describes two methods of using these plates, one of which depends upon an 

 atmosphere of hydrogen, and the other upon extracting the oxygen with pyrogalic 

 acid. The new methods suggested by the author are, therefore, the use of 

 NH4SH, as a deoxidizing agent, and of methylene blue as a test of the com- 

 pleteness of the deoxidization. h. w. c. 



