RESPIRATION 



91 



times. Oxygen debts are known to occur under experimental con- 

 ditions (Davis and Slater, 1928) but there is no evidence that similar 

 conditions occur in the field. On the other hand neurosecretory 



Fig. 27. Diurnal rhythm of O2 consumption in L. terrestris for two 



consecutive semilunar periods. A. May 2-16, B. May 17-31 and for 



the entire lunar period, C. May 2-31, 1954 (from Ralph, 1956. 



Copyright University of Chicago). 



cells may influence locomotor activity, as in cockroaches (Harker, 

 1960) and thus lead to a discrepancy in locomotor movements and 

 oxygen consumption. It seems an anomaly however, that a period 



