<4 PHYSIOLOGY OF THE HOXEY-BEEi. 



all the same. The larva is no sooner perfectly inclosed, than it 

 begins to spin a cocoon after the manner of the silk-worm, 

 and Cheshire teaches us that it does not encase the insect, 

 but is only at the mouth of the cell, "and in no case extends 

 far down the sides." 

 To return to Bevan : 



169. ''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 which it has taken 

 serves as a store for developing 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 as not 

 to wear a vestige of its previous form. ' ' 



Fig. 31. 



SPIXMXr, OF THE COCOON AND TRANSFORMATION INTO NYMPH. 



(Magnified. Frcm Sartcri and Rau3chenfels.) 



170. The last cast-off skin of the larva, "which, by the 

 creature's movements within the cell, becomes plastered to 

 the walls and joins the cocoon near the mouth end" (Chesh- 

 ire), is left behind, and forms a clcsely-attaclied and exact 

 lining to the cell; by this means the breeding-cells become 

 smaller, and their partitions stronger, the oftener they change 

 their tenants. 



So thin is this lining, that brood combs more than twenty 

 years old have been found to raise bees apparently as large 

 as any other in the Apiaiy. 



lYl. About twenty-one days are usually required for the 

 transformations from the worker-egg to tlie perfect insect. 

 But the time may be shortened or lengthened by the tem- 



