The law recognizes that under some circumstances the omission of a duty owed by one individual to another, where such omission results in the death of the one to whom the duty is owing, will make the other chargeable with manslaughter. * * * This rule of law is always based upon the proposition that the duty neglected must be a legal duty, and not a mere moral obligation. It must be a duty imposed by law or by contract, and the omission to perform the duty must be the immediate and direct cause of death. * * *