What does the phrase "butt-ends" mean?

Reading Comprehension Read the quoted parts carefully and answer the questions in English.​" And when I am formulated, sprawling on a pin,/ When I am pinned and wriggling on the wall,/ Then how should I begin/ To spit out all the butt-ends of my days and ways?"

What does the phrase "butt-ends" mean?
【正确答案】：

IT MEANS THE SPEAKER'S UNSATISFIED DESIRES.

【题目解析】：题干中的短语意思为“说话人未得到满足的欲望”。