LIFE WITHOUT OXYGEN 113 



What is true of the bacteria is equally true of the protozoa. 1 

 Thus Bunge 2 has shown that many of the more primitive 

 forms are either actively or conditionally anaerobic to a very 

 considerable degree. Vinegar eels {Anguillula aceti) lived and 

 displayed the liveliest sort of motions in complete absence of 

 oxygen during seven days, leeches during three days, Ascaris 

 five days, Haemoptis two days, Clepsina six days, Nephillis 

 two days, snails ten to fifteen hours, etc. Apparently the 

 observations were carried out at room temperature ; Pflueger, 3 

 however, has shown that the ability of the frog to resist the 

 withdrawal of oxygen is inversely proportional to the tempera- 

 ture, so that it is probable that at the ordinary temperatures 

 at which many of the slime worms live their need of oxygen is 

 still less than Bunge's observations would lead us to suppose 

 is the case. 



Bunge's work has been continued by Weinland, 4 Putter 

 and Lesser 5 among others. Putter 6 kept leeches alive during 

 ten days ; Opalina during twenty days ; he also experimented 

 with Paramecium caudatum, Colpidium colpoda, Opalina ranarum, 

 Balantidium eotzoon, Nyctotheris caudiformis and Spirostomum 

 ambiguum. Putter's conclusions were as follow : 



" In their widespread independence of molecular (free) 

 oxygen and in the dependence of the faculty of living anaerobi- 

 cally on the state of nutrition and the supply of nutriment, the 

 protozoa present a close agreement with countless plants, 

 whilst in the animal kingdom we have as yet few analogies. 

 But this is doubtless due to the fact that we have as yet few 

 experiments on the respiration of the lower animals and that 

 these even have generally been interpreted so as to agree with 

 the dogma of the invariable necessity of molecular oxygen " 

 (I.e. p. 612). 



Duclaux 7 speaks to the same effect when he remarks upon 

 the part which pure suggestion has played in the formation of 

 the ancient (but still largely dominant) theories of respiration. 



1 Cf. Prowazek, Physiol, d. Einzelligen, p. 50 (Leipzig, 1909). 



2 Zeit.physiol. Chemie, 48, 8, 1883 ; 565, 12, 1889 ; 318, 14, 1890. 



3 "U. physiol. Verbrennung," Zeit. f.ges. Physiol. 1875. 



4 Zeit.f. Biol. ; various papers in vols. 42, 43, 45, 48. 



5 Lesser, I.e. 



6 " Die Atmung d. Protozoen," Zeit.f.allg. Physiol. 566, 5, 1905. 



7 Traite de Microbiologic t. 1 



8 



