Sentence:  But after the doctor 's return that night Alex could see , from the high window in his own room , the now familiar figure crouched on a truly impressive heap of towels , apparently giving its <WSD>egg</WSD> hatching powers one final chance before it was replaced in its office by a sure-enough hen . 
Meaning of the word marked with <WSD> tags:  animal reproductive body consisting of an ovum or embryo together with nutritive and protective envelopes; especially the thin-shelled reproductive body laid by e.g. female birds