INTRODUCTION 



economic possibility and attention has so far been concen- 

 trated on the large-scale culture of forms such as Chlorella. 

 The use of mass cultures of diatoms for the production of 

 fat was first suggested by Harder and von Witsch^^^ during 

 the Second World War and the suggestion that Chlorella 

 might be used for the same purpose was made indepen- 

 dently in 1947 by Spoehr and Milner.^^^ Since high photo- 

 synthetic efficiencies can be more easily achieved and main- 

 tained with unicellular algae than with conventional crop 

 plants the idea of using these organisms for the large-scale 

 production of industrially useful organic matter is an attrac- 

 tive one and has been the subject of much speculation, 

 discussion and experiment.i^^, 262, 223. 204, 48 



In the present state of our knowledge of algal metabolism 

 the facts must to a great extent be interpreted in terms of 

 concepts established by the biochemical investigation of 

 other types of organisms. There can be little doubt that 

 the general pattern of metabolism in algae is the same as 

 that in other forms of life. Thus, it must be expected that 

 in algae life involves continual synthesis and breakdown 

 by enzyme-catalysed reactions of the substances of high 

 potential chemical energy, such as proteins and nucleic 

 acids, which make up the fabric of their protoplasm. It is 

 less certain that the chemical mechanisms involved in these 

 processes in algae are the same as those which have been 

 found in other organisms. For example, although the re- 

 markable similarity of reaction sequences found to take 

 place in such diverse organisms as yeast and vertebrates 

 suggests that the mechanisms by which carbohydrates are 

 broken down in respiration are fundamentally the same in 

 all organisms, there is not otherwise much justification for 

 assuming that the respiratory processes of algae are similar 

 to those of other organisms. The facts known concerning 

 algal respiration are worth considering at some length in 

 this connexion since this will give the best idea of the extent 

 of the correspondence between the chemical mechanisms 

 of algae and of other organisms and will also provide a 

 useful basis for the discussion in subsequent chapters of 

 processes which intermesh with respiration. 



