TEMPORAL REGULATION IN CELLULAR PROCESSES 229 



perature and illumination) is not greatly different at different but 

 constant temperatures. 



These include the following rhythms: leaf movement in Phaseolus 

 (Biinning, 1931; Leinweber, 1956); growth rate in Avena (Ball and 

 Dyke, 1954); exudation in 'Helianfhus (Grossenbacher, 1939); pho- 

 totaxis in Euglena (Bruce and Pittendrigh, 1956); sporulation in 

 Oedogonium (Biihnemann, 1955a); sporulation in Pilobolus (Schmi- 

 dle, 1951; Uebelmesser, 1954); zonation of growth in N euros jwra 

 (Pittendrigh et al., 1959); bioluminescence and cell division in 

 Gomjciukix (Hastings and Sweeney, 1957b; Sweeney and Hastings, 

 1958); mating in Paramecium (Ehret, 1959); eye pigment migration 

 in Cambarus (Welsh, 1941); color change in Uca (Brown and Webb, 

 1948); the time sense in the bee (Renner, 1957; Wahl, 1932); eclo- 

 sion in Drosophila (Pittendrigh, 1954); activity in the cockroach 

 (Bimning, 1958b); and activity in the Hzard (Hoffman, 1957). 



Many possibilities have been considered to explain the phenom- 

 enon of temperature independence (Pittendrigh and Bruce, 1957). 

 The only one which has received any substantial experimental sup- 

 port is that of a temperature-compensation mechanism. It is clear 

 that an appropriately coupled physicochemical mechanism could 

 exhibit essential temperature independence. Thus, the rate of one 

 process could be decreasing and that of another increasing such tliat 

 their net coupled output was constant. 



Various other possibilities, such as feedback control via the regu- 

 lation of enzyme activitv, have been mentioned (Hastings and 

 Sweeney, 1957a, 1959 ) . Because of our scanty knowledge concern- 

 ing the chemistry of the cycle, it is probably not fruitful to elaborate 

 in detail concerning these and other possibilities. 



We have been concerned with various biochemical aspects of the 

 rhvthmic mechanism in the dinoflagellate, Gonijaukix polijedra. The 

 studies to be described here have been concerned with the effects 

 of inhibitors. 



In previous studies utilizing inhibitors, it had generally been 

 found that the phase and the period were relatively insensitive to 

 modification by chemical agents. Biihnemann ( 1955a), studying the 

 rhythm of sporulation in Oedogonium, found essentiallv no effects 

 utilizing NaCN, 2-4 dinitrophenol, NaF, Na arsenate, iodoacetic 

 acid, quinine, copper sulfate, cocaine, y8-indoleacetic acid, adenosine 

 triphosphate, and riboflavin. Biinning (1959), studying the leaf 



