NATUKAL HISTORY OF THE HONEY-BEE. 45 



tell is made not of pure wax, but of a mixture of bee. 

 bread and wax ; and appears under the microscope to be 

 full of fine holes, to give air to the inclosed insect. From 

 its texture and shape it is easily thrust off by the bee 

 when mature, whereas if it consisted wholly of wax, the 

 insect would either perish for lack of air, or be unable to 

 force its way into the world. Both the material and shape 

 of the lids which close the honey-cells are different : they 

 are of pure wax, and thus air-tight, to prevent the honey 

 from souring or candying in the cells ; and are slightly 

 concave, the better to resist the pressure of their contents. 



To return to Bevan. " The larva is no sooner perfectly 

 inclosed than it begins to line the cell by spinning round 

 itself, after the manner of the silk-worm (PI. XIII, Fig. 

 42), a whitish silky film, or cocoon, by which it is encased, 

 as it were, in a pod. When it has undergone this change, 

 it has usually borne the name of nymph, or pupa. It has 

 now attained its full growth, and the large amount of 

 nutriment Avhich it has taken serves as a store for devel- 

 oping the perfect insect. 



" The working bee-nymph spins its cocoon in thirty-six 

 hours. After passing about three days in this state of 

 preparation for a new existence, it gradually undergoes so 

 great a change (PL XIII, Fig. 43), as not to wear a ves- 

 tige of its previous form. 



" When it has reached the twenty-first day of its exist- 

 ence, counting from the time the egg is laid, it comes forth 

 a perfect winged insect. The cocoon is left behind, and 

 forms a closely attached and exact lining to the cell in 

 which it was spun ; by this means the breeding cells 

 become smaller, and their partitions stronger, the oftener 

 they change their tenants; and may become so much 

 diminished in size as not to admit of the perfect develop- 

 ment of full-sized bees. 



