THE WONDER vS OF LIFE 



There are, as yet, no differentiated physiological func- 

 tions in these organisms without organs, and no ana- 

 tomically distinct members; and so their one vital 

 activity, growth, may very well be compared to the 

 simple growth of inorganic crystals. 



It has been pointed out repeatedly that the remarkable 

 monera which now play so important a part in biology 

 as bacteria stand, in many respects, quite apart from 

 the ordinary vital phenomena of the higher organisms. 

 This is especially true of their metabolism, which has 

 the most striking peculiarities. Morphologically, many 

 of the bacteria cannot be distinguished from their near- 

 est relatives and direct ancestors, the chromacea, differ- 

 ing from them only in the absence of coloring matter in 

 the plasm. Many of them are simple, globular, ellipsoid, 

 or rod-shaped plasma particles, without any visible or- 

 ganization or movement. Others move about by means 

 of one or more very fine lashes (like the flagellata). No 

 real nucleus can be discovered in the structureless plas- 

 ma body. The very fine granules which are found in 

 some species, and the vacuole-formation that we see in 

 others, may be regarded as products of metabolism; 

 and the same may be said of the thin membrane or the 

 thicker gelatinous envelope which many of the bacteria 

 secrete. This makes all the more remarkable the pe- 

 culiarity of their chemical constitution and the metab- 

 olism determined thereby. The nitro-bacteria we have 

 mentioned previously are plasmodomous ; the anaerobe 

 bacteria (of butyric acid and tetanus) only flourish 

 where oxygen is excluded ; the sulphur bacteria (beggia- 

 toa) secrete — by the oxydation of sulphuretted hydro- 

 gen — pure regulation sulphur in the form of round gran- 

 ules. The ferruginous bacteria {leptothrix ochrocea) store 

 up oxyhydrate of iron (by the oxydation of carbonic 

 protoxide of iron). The saprogenetic bacteria cause 

 putrefaction, and the zymogenetic fermentation. Final- 



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