52 
FIELD ORNITHOLOGY. 
the drill perpendicularly to the surface, unless it be preferred to prick with a needle first. 
A twirling motion of the instrument gradually enlarges the opening by filing away the shell, 
and so bores a smooth-edged circular hole. This should be no larger than is required to 
insert the blow-pipe loosely, with room for the contents to escape around it. Nor is it always 
necessary to insert the pipe ; a fine stream of water may be easily injected by holding the 
instrument close to the egg, but not quite touching. The blowing should be continuous and 
equable, rather than forcible ; a strong pufi" easily bursts a delicate egg. Be sure that all the 
contents are removed; then rinse the interior thoroughly with clean water, either by taking a 
mouthful and sending it through a blow-pipe, or with the syringe. Blowing eggs is a rather 
fatiguing process, more so 
than it might seem ) the 
cheek muscles soon tire, 
and the operator actually 
becomes "blown" himself 
before long. The opera- 
tion had better be done 
over a basin of water, both 
to receive the contents, and 
to catch the egg if it slip 
from the fingers. The 
membrane lining the shell 
should be removed if pos- 
sible. It may be seized by 
the edge around the hole, 
with the forceps, and 
drawn out, or picked out 
with a bent pin. But this 
is scarcely to be accom- 
plished in the case of fresh 
eggs, when the membrane 
may be simply pared 
smoothly around the edge 
of the hole. Eggs that have been incubated of course offer diffi- 
culty, in proportion to the size of the embryo. The hole may be 
drilled, as before, but it must be larger ; and as the drill is apt to 
split a shell after it has bored beyond a certain size of hole, it is often 
well to prick, with a fine needle, a circular series of minute holes 
almost touching, and then remove the enclosed circle of shell. This 
must be very carefully done, or the needle Mali indent or crack the 
shell, which, it must be remembered, grows more brittle towards 
the time of hatching. Well-formed embryos cannot be got bodily through any hole that can 
be made in an egg ; they must be extracted piecemeal. They may be cut to pieces with the 
slender scissors introduced through the hole, and the fragments be picked out with the 
forceps, hooked out, or blown out. No embryo should be forced through a hole too small ; 
there is every probability that the shell will burst at the critical moment. Addled eggs, the 
contents of which are thickened or hardened, offfer some difficulty, to overcome which persistent 
syringing and repeated rinsing are required ; or it may be necessary to fill them with water, 
and set them away for such length of time that the contents dissolve by maceration ; carbonate 
of soda is said to hasten the solution ; the process may be repeated as often as may be necessary. 
In no event must any of the animal contents be suffered to remain in the shell. When emptied 
Pig. 6. — Scissors, knives, and forceps, J nat. 
e ; after Newton. 
Fig. 7. — Hooks for ex- 
tracting embryos, nat. size ; 
after Newton, a, b, c, plain 
hooks ; d, bill-hook, having 
cutting edge along the con- 
cavity. 
