Black
Dart states, "They (Dr. Acher's folks) can be as dark as me or as light as you, but their ignorance is the same damned color wherever you find it-black." Dart cites colors to stress the extremity of Dr. Archer's extreme superstition. Dart uses the term "damned" to underscore the doomed nature of the black people. The black color invites curses based on Dart’s assertion.
Accessory
The detective asserts, “Unless you are protecting each other. In which case, if I may remind you, you become an accessory. - Come on, Doc. No doubt the family would like a private conference.” The detective is aware that the members of the household know the individual who stabbed Sonny but they are not willing to expose him. They would be alibis for willingly hiding the identity of the party that murdered Sonny. The detective’s citation of accessory to show that he is convinced that the murderer is an insider at the household.
Fingerprints
Dart states, “we can expect to find the killer’s fingerprints on this black pearl handle.” Dr. Finkelbaum adds, “That handle will name the guilty party even if he wore a glove. The new method, you know.” The fingerprints would offer hints about the stabber for they would be ascertained used scientific methods. The doctor’s affirmation informs the family that the murderer will not escape no matter the controls he/ she put in place to conceal tracks.
Thymus
Dr. Archer describes retained thymus: “A big gland here in the chest. Usually disappears after birth. Sometimes doesn’t. Untreated, it produces thus status lymphaticus-convulsions-death.” Dr. Archer’s is an expert who understands the development and effects of thymus. He is saddened for losing a young patient to the ailment for he is conscious that the patient would have been treated successfully.
X -ray
DR. Archer explains, "The kid should have had X-ray treatments. Melt the thing away. These kids, literally, choking to death in a fit, clear up and recover." Dr. Archer is certain that the sole remedy to 'retained Thymus' would be X-ray treatments. The melting alludes to the dissolution which prevents the thymus from advancing to fatal levels.
