NUTRITION 



the unicellular protists in the independent ciliated cells. 

 The longer plasmophagous flagellata, which are color- 

 less, and have no chlorophyll (monodina, conoflagellata), 

 closely resemble in form and movement the older plasma- 

 domous and chlorophyll-bearing mastigota, from which 

 they are descended (volvocina, peridinia); they only 

 differ in the manner of nutrition. The colorless flagel- 

 lata feed on ready-formed plasm, which they obtain 

 either by means of their lashes or by a special cell 

 mouth in their cell body. On the other hand, their 

 ancestors, the green or yellow mastigota, form new 

 plasm by photosynthesis like true cells. But there are 

 also complete intermediate forms between the two 

 groups — for instance, the chrysomonades and the 

 gymnodinia; these may behave alternately as protozoa 

 or protophyta. In the same way we can derive the 

 phycomycetes by metasitism from the siphonea, the 

 fungi from the algae; and, finally, the process is also 

 found in many of the higher parasitic plants (orchids, 

 orobanches, etc.). (See under "Parasitism.") 



As is the case with every other vital function, so for 

 the ftmction of metabolism we find a starting-point in 

 the lowest and simplest group of the protophyta, the 

 chromacea. In their oldest forms, the chroococcacea, 

 the whole body is merely a blue-green, structureless, 

 globular plasma particle, growing by means of its 

 plasmodomous power, and splitting up as soon as it 

 reaches a certain stage of growth. There the miracle of 

 life consists merely of the chemical process of plasmo- 

 domism by photosynthesis. The sunlight enables the 

 blue-green phytoplasm to form new plasm of the same 

 kind out of inorganic compounds (water, carbonic acid, 

 ammonia, and nitric acid). We may look upon this 

 process as a special kind of catalysis. In this case 

 there is absolutely nothing to be done by Reinke's 

 "dominants," or conscious and purposive vital forces. 



217 



