From an article entitled "Cannot Disguise It"

In microscopy Mr. Ewell hangs firmly to the theory that it is impossible to decide between the blood stains made with fluid from warm blooded animals. The microscopes can always tell whether or not suspected stains are blood, but there is no way of determining whether or not the blood once flowed through a human's veins. This was his testimony in the Cronin case as to the stains on the floor of the Carlson cottage, where the doctor was murdered. The overzealous ness of a reporter in working up a sensation for his paper prevented any testimony being taken as to whether or not the doctor was killed in the cellar.

This journalist took a beef's liver and wiped the floor of the basement with it, producing the marks of a tragedy, but destroying forever all chance of inspection of the stains. Mr. Ewell firmly holds to the belief that the Syrian who was convicted as Jack the Ripper in New York some years ago was the victim of improper expert testimony, one Philadelphia physician swearing that the blood found beneath the finger nails of the suspect was human. He offered his services to the attorneys for the defense after the fellow was convicted, but they would not move for an appeal.