ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



251 



preceding ; the series of tubes contains fluid medium ; the right amount 

 of liquid necessary to allow succeeding tubes to be filled from the pre- 

 ceding by tilting the whole apparatus, is previously tested and the levels 

 marked. The tubes are sterilised and inoculated with B. mesenteric us. 



^> ^ 



I 



/ 



Sterile cotton 

 •} wool plug before 

 sealing off 



Hygroscopic 

 wool plug 

 saturated with 

 alkalin pyrogallol 



Sterile, dry, 

 non-hygroscopic 

 wool plug 



Nutrient fluid 



Fig. 60. 



and after 10 hours the broths are clouded ; the first tube is then inocu- 

 lated with a loopf ul of B. pvtrificus broth, and all the tubes are closed 

 anaerobically as before ; subcultures were made from tube to tube every 

 two days, and after the appearance of growth in the last tube this was 

 opened, and on microscopical examination was found to be typical B. 

 putrificus, with no evidence of involution forms. Similar results were 

 obtained, in a long series, by using light bacteria in place of B. mesen- 

 tericus, and subculturing other anaerobic organisms. 



The author further modified the tubes by drawing out the upper 

 portions into narrow necks, which, after receiving the two plugs of wool 

 as before, were sealed in the flame instead of being corked (fig. 61). 



s 2 



