The opinion of a medical man is admissible upon, the condition of the human system at any given time; the nature and symptoms of disease; the nature and effects of wounds; the cause of death; the cause or effect of an injury; the character of the instrument with which a wound was produced; the effect of a particular course of treatment; the likelihood of recovery; the mental condition of a person; and on similar subjects. For instance, where one was indicted for endeavouring to procure abortion, the opinion that the woman was pregnant at the time is relevant [295]. Where the question was whether a certain |117| blow was sufficient to cause death; or whether a wound and fracture on the head was caused by a fall; or whether the fractures of the skull were caused by a gun; or whether a gun-shot wound caused death; the opinions of physicians were held admissible [296]. The opinion of medical experts will be received upon the question as to whether an abortion has been performed, or whether certain drugs are abortives, or certain instruments adapted to produce an abortion [297]. Experts may testify, after having made a chemical analysis of the contents of the stomach, as to the presence of poison in the body; and, without such analysis of a mixture, a chemist may speak of its ingredients [298]. Those accustomed to make chemical and microscopic examinations of blood and blood stains may speak as to whether certain stains are made by human or other blood. So, too, they may speak as to the ink in questions as to handwriting [299]. So, too, they may be asked their opinions touching the permanency of any injury forming the subject of an action. Also, in an action for damages against a railway company, a physician may be asked at what period after the injury the plaintiff would be most likely to improve, if he were going to recover at all [300]. Where Barber sued Meriam for injury to his wife, and she had been treated professionally for some weeks by Dr. H., the opinion of another physician as to the effect of Dr. H.’s treatment was considered |118| admissible [301]. And so in a case of malpractice a medical man may be asked whether the practice pursued was good practice [302]. He may be asked as to the nature and properties of the medicines employed by another physician in the case in question; also, as to the practice with regard to consultations; also, whether, in his opinion, a patient’s death was or was not the result of neglect or want of skill on the part of the attending physician [303]. But he cannot be asked his opinion as to the general skill of the physician on trial; nor the general reputation of the school which the doctor in trouble attended; nor can he say whether, from all the evidence in the case, the defendant was guilty of malpractice, for that is the question for the jury; nor can he say whether a physician has honorably and faithfully discharged his duty to his professional brethren [304].