WERNER MARCHAND 141 



found that they did not attack these with great alacrity, but seemed 

 rather to avoid their contact when placed near them. However, 

 after having pierced Chironomus larvae by means of a pointed scalpel, 

 Lecaillon observed some of the larvae to suck up the blood, their in- 

 testinal tract assuming a characteristic red color; he even saw them 

 penetrate into the body of the animal in order to devour it. On the 

 other hand, it was observed that the larvae placed in moist earth ab- 

 sorbed the organic detritus, giving their intestine a distinct dark 

 color. These facts led Lecaillon to assume that the larvae of Tabanus 

 quatuornotatus can feed, according to circumstances, on animal or 

 vegetable matter in process of decomposition, and probably also on 

 certain soft larvae selected by the experimenter. 



Lecaillon goes on to investigate the conditions of humidity favor- 

 able for the larvae. Generally he left them in very moist earth. But 

 once, having placed within the crystallizing dish, which contained the 

 larvae, another dish the under side of which was wet and rested on the 

 former, from which the earth had been partly removed, Lecaillon found 

 that fifteen larvae had assembled under the smaller dish, between the 

 two glass surfaces, and were completely submerged in water. He 

 subsequently placed a number of larvae in a cup filled with water, 

 and observed that they appeared to be at home in the water, remain- 

 ing in it and making no attempt to leave it. Later, Lecaillon placed 

 the larvae which he intended to rear in mud taken from an aquarium ; 

 they remained completely burrowed in this mud and could even find 

 nourishment in it. 



On the other hand, Lecaillon repeatedly allowed the earth in which 

 larvae were kept to dry out completely and found that the larvae not 

 only did not suffer but remained quite active. 



His conclusion was that the larvae of Tabanus quatuornotatus are 

 capable of adapting themselves to a variable degree of humidity, and 

 can live, at least for some time, in dry ground as well as in water. 

 Concerning the range of humidity, and also concerning food habits, 

 these larvae, as probably other tabanid larvae also, appear not to be 

 adapted to limited conditions, in contrast to many other insects. 



In his later publication, Lecaillon emphasizes the great resistance 

 of the larvae of Tabanus quatuornotatus to humidity and draught, ex- 

 plaining the fact by the presence on the body surface of a chitinous, 



