In a medical malpractice case, a jury verdict finding defendant-doctor negligent in his care of decedent, but not liable for his death because his negligence was not a proximate cause of harm to decedent, is reversed where the trial judge erred in: 1) failing to permit the testimony of defendant's medical expert that was favorable to plaintiffs; and 2) in permitting defendant to opine on issues of causation without providing proper notice to plaintiffs.