306 LOCOMOTORY AND PROTOPLASMIC MOVEMENTS 



The plasmodia of Myxomycetes may, however, with equal readiness ingest and expel 

 indigestible particles such as grains of sand or of vermilion. In addition, mere contact 

 with non-motile regions of the ectoplasm is insufficient to produce ingestion, which 

 takes place usually only at those regions where amoeboid activity is shown. 



PART II 



THE INFLUENCE OF THE EXTERNAL CONDITIONS ON LOCOMOTION 

 AND ON PROTOPLASMIC MOVEMENT 



SECTION 65. 



Under special external conditions the power of active locomotion 

 may be inhibited without growth ceasing, and the contrary may also occur. 

 A. Fischer * found that various bacteria become immotile in concentrated 

 solutions in which they grow and develop motile cilia. The presence of 

 carbolic acid, and in general any agency which when more intense suppresses 

 growth, may produce the same effect. Temperatures lying near the 

 maximum may act in the same way, but Matzuschita 2 did not determine 

 to what degree the immotility was due to the production of non-ciliated 

 developmental forms. Prolonged cultivation on solid media has, for in- 

 stance, always this effect upon the motile aerobic forms of Bacterium termo 

 used for testing the evolution of oxygen 3 . According to Ellis 4 , the 

 immotility is often due to the production of mucilage which mechanically 

 prevents movement, while Ritter 5 found that facultatively anaerobic 

 bacteria lost their motility in the continued absence of oxygen, but 

 immediately regained it when oxygen was admitted. 



Most locomotory and protoplasmic movements take place in darkness 

 as well as in light, whereas the purple bacteria which develop normally in 

 darkness 6 only begin to move when exposed to light, and fall into a con- 

 dition of dark-rigor when it is withdrawn. In addition, other phototonic, 

 thermotonic, and chemotonic actions upon locomotory activity are known. 

 Many substances, such as ether and chloroform, which when concentrated 



1 A. Fischer, Jahrb. f. wiss. Bot., 1895, Bd. xxvn, pp. 48, 153. 



2 Matzuschita, Centralbl. f. Bact., Abth. ii, 1901, Bd. vn, p. 209. 



3 Ewart, Journ. Linn. Soc., 1896, Vol. XXXI, p. 364. 

 * Ellis, Centralbl. fur Bact., 1902, Bd. IX, p. 546. 



8 Ritter, Flora, 1899, p. 337. 



6 [This appears to be an error. The purple chlorophyll-containing Bacterium photometricuin 

 and Monas Okenii will develop in feeble light but not in continued absolute darkness, even when 

 sown on various solid and liquid nutrient media. The green bacteria {Bacillus virens, Bacterium 

 chlorinum, and Streptococcus varians) may, however, be grown in darkness on gelatine-sugar media, 

 but then lose their chlorophyll. Cf. Ewart, Journ. Linn. Soc., 1897, Vol. xxxill, p. 123, and Annals 

 of Botany, 1897, v l - XL P- 4 8 6-] 



