ANIMAL AVOCATIONS 247 
builder and the mason. The birds are, of 
course, the most familiar of those animals that 
specialize in building operations, but many 
mammals, such as the beaver, the squirrel, 
the harvest mouse, and others too numerous 
to mention, exhibit wonderful constructive 
ability in the building of their homes. As, 
however, our remarks upon animal avoca¬ 
tions have already extended to a considerable 
length, we must reserve to a future occasion 
a more detailed description of these interesting 
animals. 
In the mason wasp we have a creature that 
copies the work of the human mason by mixing 
up fine particles of earth with its own saliva, 
thereby producing a mortar that forms a hard 
substance when dry, the same being utilized 
in the formation of small tubular cells, about 
an inch in length, that are fixed to various 
objects such as a pebble, a wall, or the branch 
of a tree, and wherein the female insect lays 
her eggs. When the cells are completed the 
wasp proceeds to provide for the needs of her 
prospective family by placing small cater¬ 
pillars inside to serve as food when the grubs 
hatch out, the caterpillars being rendered 
inactive, but not being killed, by the wasp, who 
stings them in such a manner as to paralyse 
them. 
