* 
166 NATURAL HISTORY OF WASPS. 
passes behind the left set of egg tubes, which we 
must divide before we can trace the further course of 
the canal. 
As we now draw the stomach gently forwards, 
gradually tearmg away the fine trachee which closely 
surround and retain it in its place, a yellowish floccu- 
lent mass comes into view, chiefly composed of threads 
at once distinguishable from the white air tubes with 
which they are entwined. These yellow threads are 
a system of gland-tubes, which enter the alimentary 
canal at the le of demarcation between the stomach 
and the small intestine. The line is a little wider 
and less definite in the wasp than in the honey-bee, 
but m both equally it indicates the point where the 
canal changes its functions, where the stomach ends 
and the small intestine begins. Probably we shall 
break the alimentary canal of a good many wasps, at 
this delicate point, before we succeed in obtaining a 
specimen of the tube, perfect and continuous in its 
entire length. For not only is it very soft here and 
easily torn, but this is one of the narrowest points in 
the whole intestinal tract. From the extreme narrow- 
ness of the passage here, at the outlet of the stomach, 
it would seem that very little of what is taken into 
the stomach is intended to pass through it undigested. 
The economy of the larve of the wasp differs, how- 
ever, materially from that of the perfect insects in this 
respect, hard indigestible matters forming, as we shall 
see presently, an appreciable proportion of the food 
with which they are supplied by their nurses. But, 
if the wasp’s mandibles are not adapted to grind hard 
substances into a pulp, wasps have a most effectual 
protection against any large masses, which might 
