THE OXE-BANDED DAUBER 65 



place within. This spasm is a sort of pumping wave, similar to the 

 movement in a big fire hose under pressure from the engine. It 

 starts at the anterior end of the egg and traverses its entire length, 

 fading out as it reaches the opposite end from which it started. Thus 

 does the new-born take its first mouthful of liquid food from the 

 spider. There is no actual hatching and crawling forth from the 

 egg, no empty shell behind the larva. Instead, its mouth appears 

 first to eat a tiny opening through the film that encloses it, after 

 which the grub finds its mouth flat upon the spider's abdomen. As 

 the pumping spasms continue, each one representing a swallowed 

 mouthful of spider substance, the nursling increases very gradually 

 in bulk. In a few hours after taking its first draught of foodstuff, 

 the egg-film apparently splits along the center of the larva's back, 

 one end of the breach traveling in either direction, exposing the 

 actual skin of the young wasp. The breach spreads like a drop of oil 

 upon water, only much more slowly, but twenty-four hours after 

 the first spasm not a vestige of film remains. It appears to have been 

 absorbed into the larva's body. Under the lens it vanishes slowly 

 before my eyes, yet I cannot see where it goes, and when the process 

 is over I can find no trace of it, either on the larva or its spider host. 

 The grub is a living dialyzer through w r hose delicate skin the egg- 

 film appears to osmose. In other words, I believe that the film is 

 absorbed into the insect's body in minute particles in much the same 

 manner that food passes through the walls of the oesophagus to reach 

 the distributing corpuscles. 



It is possible that the larva eats the egg-film, but if so it is drawn 

 into the mouth so gradually and with such skill that it is impossible 

 to detect the operation. Therefore, I suggest that the process may 

 be akin to osmosis. The action is so gradual, so smooth and unin- 

 terrupted that I can think of no other way to describe it. 



At first the young wasp lives only on liquid foods. During the 



