The next transformation is to the nymph or pupa form. The nurse bees now seal up the cells with a preparation similar to wax, leaving them with coverings which, by their greater convexity and darker colour, distinguish them readily from honey cells. The pupa then spins round itself a film or cocoon, just as a silkworm does in its chrysalis state: workers and drones occupy thirty-six hours with this process; princesses, which spin only half-cocoons, finish them in twenty-four. The microscope shows that this cradle-curtain is perforated with very minute holes, through which the baby bee is duly supplied with air. No farther attention on the part of the bees is now requisite, except a proper degree of heat, which they take care to keep up--a position for the breeding cells being selected in the centre of the hive, where the temperature is likely to be most congenial. The cells destined for the rearing of drones are larger than those from which workers will proceed, the former standing nineteen to the square inch against twenty-seven of the latter: the former are also one-third as deep again as the latter, and are made slightly more convex when sealed over. But between the eggs themselves there is externally no difference whatever. In from nineteen to twenty-one days after the egg is first laid (unless cold weather should have retarded it) the bee quits the pupa state, and, nibbling its way through the waxen covering that has enclosed it, comes forth a winged insect. The eggs of drones require twenty-four or twenty-five days, and those of queens sixteen or seventeen, to arrive at maturity. In the unicomb observatory hives the young bees may distinctly be seen as they literally fight their way into the world, for the other bees do not take the slightest notice, nor afford them any assistance. We have frequently been amused in watching the eager little new comer, now obtruding its head, and anon compelled to withdraw into the cell to escape being trampled on by the apparently unfeeling throng, until at last it has succeeded in making its exit. The little grey creature, after brushing and shaking itself, enters upon its duties in the hive, and after a while issues forth to the more laborious occupation of gathering honey in the fields--thus early illustrating that character for industry which has been proverbial at least since the days of Aristotle, and which has in our day been rendered familiar even to infant minds through the nursery rhymes of Dr. Watts. § IX. REPRODUCTIVE ECONOMY.