The white elephant might symbolize the couple's unborn child in this story, If the phrase of white elephant means a property requiring much care and expense but yielding little profit. The couple’s unborn child is the one that the white elephant symbolize in this story.
Is very simple, although the term "chaser" may not be as commonly used as it was when John Collier wrote his story. A chaser is a drink that is taken to follow the first alcoholic drink.