1812 Journal of Applied Microscopy 



differentiation of species it becomes necessary, therefore, to use various kinds of 

 special media, and as it is of great importance, if accurate and reliable results 

 shall be obtained, that the temperature and atmospheric conditions under which 

 the cultures are made should be as uniform as possible, it is obvious that large 

 apparatus, such as Gabinsky's especially, which will permit a large number of 

 culture tubes simultaneously, are most adapted for this work. 



4. Methods for the propagation of pure cultures and the preservation of stock 



cultures. 



Where it is desirable to have on hand cultures, fluid or solid, of anaerobic 

 species for the study of morphological and physiological characters, it is neces- 

 sary to use methods that are simple, permit prolonged growth of the organism, and 

 from which culture material may be obtained without difficulty. As valuable 

 methods for this purpose may be named Smith's fermentation tube containing 

 ordinary peptonized bouillon and small sterile pieces from internal organs of 

 rabbits, guinea-pigs, pigeons, etc. (V. f.), Wright's tube (V. e., Figs. 46 and 47), 

 or Liborius' method (V. a.). For stock cultures of anaerobic bacteria Liborius' 

 deep layers (V. a.) are most satisfactory. i 



5. Methods for the preparatio7i of toxins. 



Where anaerobic bacteria are cultivated for the purpose of extracting toxins 

 from the culture medium, apparatus that permit liquid cultures in large quantities 

 can only be considered. For this purpose Kasparec's apparatus (V. c, Fig. 39) 

 will serve, Park's modification of same (V. c.) and the two apparatus invented 

 by Smith (V. f.. Figs. 51 and 52). 



NUTRIENT MEDIUM. 



While, generally speaking, most of the nutrient media prepared for the culti- 

 vation of aerobic bacteria will also serve, and are constantly used for anaerobic 

 cultures, experience has shown that the latter are more exacting in their require- 

 ments of favorable media. It is not the author's intention to enter into a detailed 

 discussion of the preparation of the media, as such instruction can be obtained 

 from text-books and laboratory directions in bacteriology. What applies to 

 aerobic species, will also hold true for the anaerobes. It is impossible to give a 

 hard-and-fast rule, which embraces the media adapted for anaerobic bacteria as a 

 group. Individual species may have their individual peculiarities which call for 

 special media or media which have proved to be most favorable for their growth. 

 On the other hand, it is deemed of value to draw the reader's attention to a few 

 of the most important factors, in which the requirements of anaerobic bacteria 

 seem to differ from those of the aerobes. 



1. Composition of tnedium. 



Little need be said here as the composition of media has already been dis- 

 cussed in chapter IV on the reduction of oxygen ; the same chapter contains a 

 summary of the composition of media, which Novy (1893) found to be especially 

 adapted for anaerobic cultures. This author, who has made a careful study of 

 the ingredients of nutrient media that are most suited for anaerobic development, 



