250 MICRO-ORGANISMS IN WATER 



xvii. pp. 125 and 129) made some investigations in 

 wliich he demonstrated that bacteria in liquid culture 

 media multiplied when subjected to slight movements, 

 but that when violently agitated under otherwise simi- 

 lar conditions no multiplication took place. From 

 these observations he concluded that a certain degree 

 of movement may hinder, and even entirely prevent, 

 the multiplication of bacteria. Similar results were 

 obtained previously by Paul Bert. C. v. Nageli {Theorie 

 der Gdhrung^ Mlinchen, 1879, p. 88) exhaustively criti- 

 cised the theories and experiments of Horvath, and 

 stated that although he did not regard his assumptions 

 as incorrect or impossible, yet he considered it of the 

 greatest importance that the experiments should be 

 repeated with better culture media and at lower tem- 

 peratures. E. Ch. Hansen [Jusfs hotanischer Jahres- 

 • bericht^ 1879, p: 556) was unable to support Horvath's 

 hypothesis without further confirmation, inasmuch as 

 he found that Saccharomyces cerevisise, when cultivated 

 in beer-wort, grew better whilst it was stirred round 

 than when it was left at rest. J. Eeinke [Pflugers 

 Archiv /. Physiologie, 1880, xxiii. p. 434) carried out 

 some investigations on the effect of mechanical agita- 

 tion upon bacteria, in which he was guided by Nageli's 

 criticisms. Eeinke not only employed the motion of 

 translation as did Horvath, but also the molecular 

 motion obtained in longitudinal sound waves. These 

 experiments confirmed Horvath's, inasmuch as it was 

 found that molecular motion retarded the growth and 

 multiplication of the bacteria. Eeinke remarks, how- 

 ever, that he has no proof that it would be possible to 

 obtain a form of mechanical movement which, by con- 

 tinuous application, would kill the bacteria- Buchner 

 {Sitzu7igsberichte der konigl. hayer. Akademie der Wissen- 

 .schaften, Mathem.-physik. Klasse^ 1880, Heft. iii.,pp.382 



