INTRODUCTION 
XXXI 
of the back, if the bird is a male, you will see the two oval, usually 
light colored testes, — in the breeding season large and conspicuous, 
at other seasons small, and, in immature specimens, often difficult to 
find. If the bird is a female, in place of the two oval bodies there 
will be the ovary, a mass of spherical ovules, large or small ac¬ 
cording to the season, and often obscure in immature specimens. 
The male sign is Mars’ arrow (£), the female, Venus’ mirror ($>). 
Collecting and preserving eggs. — Egg collecting is justifiable only 
when the collector’s earnestness of purpose warrants the sacrifice of 
happy bird homes, and no amount of pains and care should be 
spared to make each set a permanent and valuable illustration of 
the life history of the species. So far as possible only complete 
sets of fresh eggs should he taken. An incomplete set is of sec¬ 
ondary importance, and eggs in which incubation is advanced are 
not worth troubling with unless very rare. 
The first step is to identify the nest positively, which, in cases of 
rare species, can often be done only by collecting one or both of the 
birds. Eggs are worse than worthless if there is any question of 
their identity. 
The next step should be to photograph the nest from at least two 
points, one to show general setting and one at closer range to give 
detail of form and structure. Then notes should be made on the 
position, structure, and materials of the nest, the actions of the old 
birds, and the manner of identification, etc. When possible the 
nest should also be collected. 
Each egg should be wrapped in cotton and each set packed snugly 
in a wooden box with plenty of cotton for carrying home. 
The tools necessary for blowing eggs are a slender blowpipe and 
two drills, large and small, which can be bought of any dealer in 
naturalist’s supplies. 
For drilling, hold the egg lightly between the thumb and two 
fingers of the. left hand, and placing the sharp point of the drill 
against the side twirl it evenly with a slight pressure until it sinks 
into the shell, grinding out a smooth round hole which points down¬ 
ward, from the size of a pin-head in a fresh sparrow’s egg to an 
eighth of an inch in diameter in a larger or partly incubated egg. 
In much incubated eggs it is often necessary to make a much larger 
opening. A fine stream of air should be forced into the egg without 
touching the blowpipe to the opening, and the contents gently forced 
out. When the shell is empty, with mouth full of water blow a 
stream into it and rinse out thoroughly, afterwards blowing all the 
water out and laying carefully away to dry. 
