332 PHYLUM ARTHROPODA. 
glands. Each egg is enclosed in an oval shell, in which 
there are several little holes (micropyles), through one of 
which a spermatozoon enters. Spermatozoa, from the store 
within the spermatheca, are included in the egg-capsule. 
At an early stage in development some cells associated with the 
mesoderm are set apart as reproductive cells, and originally these have 
a segmental arrangement as in Annelids; at a later stage other meso- 
derm cells join these, some forming ova, others epithelial cells around 
the latter. The distinction between truly reproductive cells and 
associated epithelial cells, which is said to be late of appearing in some 
of the higher insects, is established at a very early stage in the 
cockroach, 
Second Type of Insects.—The British Hive-BEE 
(Apis mellifica) 
This is a much more highly specialised type than the 
‘cockroach. It belongs to the order Hymenoptera. 
Habits.—The Hive-Bee (Apis mellifica) is a native of 
this country, and is the species most commonly found 
domesticated. It is the only British representative of the 
genus 4s, and exhibits, in its most fully developed form, 
the social life which is foreshadowed among the Humble- 
Bees. As a consequence of this social life, there is much 
division of labour, which expresses itself alike in habit and 
in structure. The males (drones) take no part in the work 
of the colony, and are wholly reproductive ; the females 
include the queen-bees and the workers. In the workers, 
which perform all the work of the hive, the reproductive 
organs are normally abortive and functionless. In the 
queens, of which there is but one adult to each hive, the 
enormous development of the reproductive organs seems to 
act as a check upon the brain and other organs, which 
are less developed than in the workers. The workers are 
further divisible into nurses, which are young and do not 
leave the hive, being occupied with the care of the larvee, 
and the older foraging bees, which gather food for the whole 
colony. 
In consideying the relation between the life of the Hive- 
Bee and that of many allied forms (Boméus, etc.), it is 
important to notice that the habit of laying up stores of 
food material for the winter enables the colony, and not 
