Physiology 433 



Autotrophic nutrition 



This general variety of nutrition,- in which inorganic nitrogen is 

 adequate for growth, is sometimes considered a primitive type which was 

 gradually lost during the "regressive" evolution of heterotrophs. Another 



TABLE 8. 2. REPORTED CASES OF "AUTOTROPHIC" NUTRITION 



IN FLAGELLATES 



* Supplementary growth-factors said to be required; CP, cotton plugs used in culture 

 tubes or flasks; NC, glass-covered culture vessels. 



view (210, 411) is that the evolution of autotrophic organisms has in- 

 volved the acquisition of synthetic abilities lacking in more primitive 

 ancestral types which were dependent upon the environment for critical 



- In this chapter, the following terms will be applied to species which can obtain 

 their required nitrogen from inorganic sources: (1) photoautotroph, or photosynthetic 

 autotroph, utilizing the energy of light; (2) chemoautotroph, or chemosynthetic auto- 

 troph, obtaining energy from inorganic substrates; (3) heteroaiitotroph, requiring an 

 organic source of energy (e.g., acetate, lactate, ethanol). 



