176 WILLIAM BRODBECK HERMS 



if the feeding period ended during the daytime the larvae escaped 

 by means of an opening eaten through the side of the dead fish 

 nearest the earth, and thus made their way into the sand beneath, 

 without much exposure to dayhght. This behavior was supposed 

 at first to be due to the heated condition of the sand during the 

 day, since on very cloudy days when the sand was cool, the open 

 migration was occasionally observed. The concealed migration 

 is of much value to the larvae, since they are thus protected quite 

 largely from the ravages of birds, though the sandpipers may be 

 found busily patrolling the beach in the dead of night, very 

 probably devouring numbers of larvae, as evidenced by their 

 tracks about fish carcases from which the larvae had migrated. 

 On very cloudy days I have observed these birds feeding on the 

 chance migrating individuals. Furthermore, during the day the 

 sand of the beach usually becomes extremely hot (commonly 78° C. 

 just beneath the surface) and larvae attempting to migrate at such 

 a time are literally baked, as has been demonstrated (Herms, '07, 

 p. 52). The concealed method of migration prevents such fatali- 

 ties to a considerable extent. 



It was also frequently oberved that the larvae feed in far more 

 unprotected positions with regard to light during the night than 

 is the rule during the day; even occasional short excursions away 

 from the flesh are taken at this time as the migration period draws 

 near. 



There remains to be considered then the range of intensity 

 through which these larvae react and the manner of their reaction. 

 The positive reaction, as already mentioned, needs also to be 

 considered in further detail. 



2. Observations and experiments 



For experimental purposes at the Lake Laboratory, eggs were 

 collected during the previous day in order that the larvae might 

 hatch under observation the following morning. On hatching, the 

 larvae immediately crawl away from the egg shells into darker, 

 less exposed situations and frequently underneath the fish, where 

 there is moisture. Moisture is an important factor in the move- 



