Section 6. Upon conviction of murder in the first degree, the court may order the body of the convict after his execution to be dissected. The warden of the state prison shall in such case deliver it to a professor of anatomy or surgery in a medical school established by law in the commonwealth, if so requested; otherwise, he shall, unless the convict’s friends desire it for interment, deliver it to any surgeon attending to receive it who will undertake to dissect it.