An injection apparatus for injecting and/or removing substances from
subjects, such as avian eggs, includes an injection needle having a body
portion and a tapered portion that terminates at a tip. A tube is
attached to and extends around the injection needle in substantially
concentric relationship therewith. The tube has an end portion positioned
a predetermined distance from the needle tip. The tube end portion acts
as a stop to limit the distance the needle tip can be inserted into a
subject, such as an egg, through a membrane of the subject. A detector
may be utilized to measure force exerted on a membrane of an egg by a
stop attached to a needle. Force exerted on a membrane by a needle and/or
by a needle and a stop attached to the needle may also be measured.