PAPERS ON PSYCHOLOGY AND PHYSIOLOGY 113 



than the other, there was nothing approaching period- 

 icity in the phenomenon, and no continuation of it was 

 noticed." (16) 



''During these visits we noted that the illumination 

 was never due to a truly synchronous lighting of the 

 lamps of those fireflies engaged in the display but was 

 always of the nature of wave motion spreading out from 

 one or more centers * * *. Strictly speaking there 

 was no measured regularity in this concerted response 

 and therefore no true rhythm. * * *" (13) 



In the most recently reported experimental investiga- 

 tion in the subject, the Snyders (27) observed a regular- 

 ity in the synchronism with a variation of only a tenth 

 of a second in the flash of fireflies flying in a strata of a 

 uniform temperature coefiicient. 



(b) Variations occur also in the statements concern- 

 ing the duration of the synchronism. Some say that the 

 effect lasted for a considerable length of time, others that 

 it appeared sporadically. One of the quotations given 

 above (16) referred to the fact that there was no con- 

 tinuation of effect noticeable. In one report we note 

 that the synchronism did not begin at the first appear- 

 ance of the flashing: 



''After a while a most remarkable synchronism in the 

 flashing ajo^Deared to take place * * *. This remark- 

 able sjTichronism in the flashing sometimes continued 

 several times in succession, * * *." (1) 



(c) The question of alternate illumination of trees, 

 in addition to the synchronous effect in any one tree, also 

 arises. There seems to be, in other words, a spatial fac- 

 tor in the distribution of the j^eriodical effect. 



In respect to the problem of rhythm, we are at once 

 confronted with several important factors. There can 

 be no rhythm, of course, unless there is accentuation of 

 some member in the measure. It is likely therefore that 

 whenever the term is used in these discussions there is 

 meant simply a periodicity or s\Tichronism, i. e., the 

 wider usage of the term common in some connections, as 

 physiological rhythm, geological rhythm, or, as is less 

 likely, there is already a tacit admission that a rhAi;hm 



