5l6 W. F. LOOM IS 



arterial blood shall have a pCOo of 5-3",, atm. at all times. Many students 

 believe that breathing is regulated by CO^ as an indirect means of con- 

 trolling the oxvgen in the blood. In fact, the body is immune to changes in 

 oxygen tension within wide limits as may be demonstrated by the lack of 

 any bodily reaction to breathing pure oxygen when at sea-level. 



Living cells then react to free or gaseous CO2 in a manner that is 

 different from their reaction to the bicarbonate ion. This difference be- 

 tween pCO., and total CO., is fundamental to any understanding of 

 biological crowding effects and stems from the little-known fact that CO2 



Gas exchange 

 tower X 



Control 

 Compressor house 



Algal suspension 

 Culture medium 

 COg-air 

 Water 



Cooler 



Gas burner 



Mixing 

 tank 



Pump 



Fig. 4. Diagram of algae plant. 



is a fat-soluble gas that is 1-67 times more soluble in lipoid solutions such 

 as olive oil than it is in water (o ). This lipo-solubility enables the free CO., 

 molecule to pass through a fatty cell wall when the bicarbonate ion can not, 

 the cell membrane therefore acting as a semi-permeable membrane that 

 distinguishes between free and bound CO., molecules. These facts are well 

 known to plant physiologists, for they have found that photosynthesizing 

 algae can only obtain the large amounts of CO2 that they require from 

 gaseous CO2 which can penetrate their cell walls when the bicarbonate 

 can not. Any algae farm therefore has two characteristic features: (Fig. 3) 



