ADENOSINE TRIPHOSPHATE 107 



(iv) Malonate (sodium salt or acid) reduces the ciliary activity 

 of oyster gills (Usuki, 1956c), sperm motility (Mann, 1954) and 

 the oxygen consumption of the sea-urchin sperm (Mohri, 1957b). 

 It blocks stage 23, but stimulates stage 25, so that Mohri found 

 that the total dehydrogenase activity may be increased in malonate, 

 particularly if malate is added. 



(v) Sodium cyanide reduces the respiration and ciliary activity 

 of Mytiliis gill (Gray, 1924; Aiello, 1960) and reduces the 

 activity of oyster gill cilia (Usuki, 1956b) and spermatozoa 

 (Mann, 1954). It prevents the action of cytochrome oxidase and 

 blocks stage 29. In oyster gill tissue, Usuki and Okamura (1956) 

 found some accumulation of pyruvic and lactic acids in the 

 presence of cyanide. 



(vi) Fluoroacetate, which blocks stage 18, was found to reduce 

 the oxygen consumption of sea urchin sperm (Mohri, 1957c). 



(vii) Chloral hydrate, which probably blocks stage 7, has been 

 shown to reduce the rate of respiration of Mytilus gill tissue 

 slightly and to markedly reduce the activity of the gill cilia (Gray, 

 1924). It appears that chloral hydrate may have a secondary 

 effect on the ciliary mechanism. 



There is thus abundant evidence that the respiration of ciliated 

 tissues normally involves both anaerobic glycolysis, the tri- 

 carboxylic acid cycle and the cytochrome system. The part 

 played by adenosine triphosphate (ATP) as a short-term energy 

 store and an energy carrier between these respiratory processes 

 and the ciliary mechanism is discussed in the next section. 



9. Adenosine Triphosphate and Ciliary Activity 



It seems well established that ATP provides the immediate 

 source of energy for the beating activity of cilia in much the same 

 way as it does for the contraction of muscle. Much of the evidence 

 for this is derived from the use of "^^ models " of cilia and flagella, 

 but some direct evidence is available. 



Vorhaus and Deyrup (1953) found that the activity of cilia 



from the pharyngeal mucosa of the frog could be increased by up 



.to 100 per cent by the addition of ATP at a concentration of 



l'5xlO~^mol, while smaller increases in activity were obtained 



at higher and lower concentrations. Hydrolysis of the ATP 



