RESPIRATORY K AT ABOLISH IN ANAEROBES 531 



of oxygen in spite of the feeble fermentative power which they possess l '. 

 Hitherto permanent anaerobes have been found only among bacteria, but 

 it is not as yet certain in all cases whether the anaerobiosis is temporary or 

 permanent 2 . 



Many pathogenic bacteria have acquired the power of anaerobiosis 

 in adaptation to the special conditions under which they exist, and it is 

 of great importance in the economy of nature that the processes of 

 decomposition may be able to continue in the interior of organic masses 

 where no free oxygen may be present. As soon as the putrefactive 

 processes consume the whole of the available oxygen, the facultative 

 anaerobes commence to live anaerobically as far as the nature of the 

 food-material will allow, while the dormant anaerobic spores germinate 

 and multiply. As the disintegration is completed, oxygen finds more 

 and more ready access to the interior and the anaerobic germs cither 

 die or pass into a resting condition. It is possible that for certain 

 organisms the continual recurrence of aerobic and anaerobic modes of 

 existence may be essential, and that such organisms are unable to develop 

 either as permanent aerobes or as permanent anaerobes, but this is a 

 question which is still open to discussion. There can be no doubt, however, 

 that a change in the external conditions must always exercise a certain 

 stimulating effect upon an organism, and hence it is possible that in some 

 cases the alternation between two modes of existence may become an 

 essential condition for continued existence. 



Anaerobic germs are nearly always present in mud, soil, &c., and form 

 colonies when inoculated upon oxygenless media. Of these some develop only in 

 the absence of oxygen, but others also when it is present. But little is known of 

 the species thus obtained 3 . 



Obligate anaerobes are : various butyric bacteria (Gramdobacter saccharobuty- 

 ricum, G. butyricum \ a few lactic bacteria (Sect. 103), Spirillum desulfuricans\ 

 Bacillus denitrificans r \ Clostridium foetidum, Bacillus polypiformis, B. tetani, B. 

 oedematis maligni (Fliigge, 1. c.). The anaerobic Clostridium pasteurianum can 

 live aerobically in symbiotic union with certain other bacteria 6 , and the bacillus 

 of cattle-plague, Bacillus carbonis, Mig., may under special conditions develop as 

 an aerobe 7 . 



1 Brefeld, Landw. Jahrb., 1876, Bd. V, pp. 293, 313; Diakonow, Ber. d. Bot. Ge*., 1896, p. a ; 

 Beyerinck, 1893, 1. c., p. 47. 



2 On certain temporarily anaerobic worms, cf. Bunge, Zeitschr. f. physiol. Chemie, 1883, Bd. VIII, 



p. 48; 1888, Bd. xn, p. 565. 



3 See the literature, and Fliigge, Mikroorganismen, 1896, 3. Aufl., Bd. I, p. 127; Libc ms, 

 Zeitschr. f. Hygiene, 1896, Bd. I, p. 169. 



* Beyerinck, Centralbl. f. Bact, 1895, Abth. ii, Bd. I, p. 59. 

 5 Burri u. Stutzer, ibid., p. 43 r. 



8 Cf. Sect. 69. -Kedrowski (Zeitschr. f. Hygiene, 1895, Bd. xx, Heft 3) mentions other examples. 

 7 Kitt, Centralbl. f. Bact., 1895, Bd. xvn, p. 168. 



M m 2 



