INGORGEMENT OF AIR 105 
“Hereby the volume of the mosquito is considerably increased; the pupal 
case can no longer hold it, and, at a time when the hind end of the body still 
remains exactly in the same position as during the pupal stage, the greatly 
lengthened body is already forced a considerable distance through the slit in the 
thorax. Through the ingorged air the abdomen loses its limpness, it is stiffened 
like an air-inflated bladder and continues to increase in volume proximally. 
The conical form of the body thus brought about causes it to glide forward in the 
anally narrowed pupal skin, and under normal conditions this motion needs 
hardly any assistance from the abdominal muscles. 
“The specific weight of the animal is greatly diminished by the taking in of 
great quantities of air, a circumstance which is equally important for the imago 
when issuing and immediately after.” 
It appears from the observations of Eysell that the three diverticula of the 
cesophagus perform an important function at this time, they receive the swal- 
lowed air and it is by their means that the volume of the insect is so much in- 
creased. During the pupal stage the diverticula contain no air whatever, but 
immediately after ecdysis they are found inflated to the utmost. We have 
already discussed (page 78) the double function of the large diverticulum and 
shown that in the mature insect it serves as a food-reservoir. The two smaller 
diverticula remain filled with air at all times. 
