62 WALTER N. HESS. 



according to these same authors, function as a suction pump in 

 drawing the liquid food into the mouth. Vogel also described 

 how the mid-intestinal secretions are forced forward, by means 

 of heavy oblique and circular pro-ventricular muscles, into the 

 mouth and out through the mandibular canals. 



Though the intestinal juices were not observed passing through 

 the canals of the mandibles, a rather dark-colored liquid was seen 

 suspended from the ends of the long curved teeth and on the 

 bodies of snails and earthworms in the region where the larvae 

 were feeding. It, therefore, seems very probable that a certain 

 liquid, which, since the larvae have no salivary glands, must 

 come from the region of the mid-intestine, is exuded through the 

 canals of their mandibles and out through the mouth, and that 

 this liquid functions in paralyzing and digesting the tissues of 

 their prey. 



The larvae were observed, however, to take into their mouths 

 portions of food of considerable size. The fact that they can 

 take up mouthfuls of earth and masticate it in the construction 

 of their pupal-cells is evidence that the larvae are able to take into 

 their mouths small masses of food before it is completely digested. 

 Yet there can be little doubt but that the-greater part of the food 

 is digested outside of the body and taken in through the mouth, 

 in the liquid state. Whether the mandibles function in the 

 intake of food was not determined, but the greater part of it 

 was apparently taken in through the mouth. The portions of 

 undigested food that were taken into the mouth, were no doubt 

 largely digested here before passing en into the intestine, as 

 the larvee masticated these masses for a considerable time before 

 they disappeared. 



The larval light-organs are fully developed at birth, so the 

 larva is luminous from the time that it hatches until it finally 

 enters the pupal state. As stated before, the light is emitted 

 from two elliptical areas on the ventral side of the eighth ab- 

 dominal segment. The larval light-organs do not emit light in 

 flashes, as the organs of many adults do, but on the other hand, 

 the glow is nearly uniform. While the larvae were active, the 

 light was found to glow continuously. During the dormant 

 periods, as during the day, but especially during hibernation, 



