Of the physiological, the four principal ones are cessation of menstruation, increase of size, quickening, and the fetal heart beat. CESSATION OF MENSTRUATION in a married woman may ordinarily be considered a sign that conception has taken place. Yet suppression may be the result of cold, of inflammation, of some chronic uterine diseases, more especially dropsy or tumors, also of any slow, wasting disease like scrofula, consumption and diarrhea. Occasionally, too, women menstruate during the entire time of gestation. This, without doubt, is an abnormal condition, and should be remedied, as disastrous consequences may result. Also, women have been known to bear children who have never menstruated. Pregnancy seldom takes place where menstruation has never occurred, yet it frequently happens that women never menstruate from one pregnancy to another. In these cases this symptom is ruled out for diagnostic purposes. INCREASE OF SIZE begins to be experienced at about the third month, when the uterus enlarges and rises above the brim of the pelvis. Any enlargement previous to this time must be due to bloating, flatulence or excess of fat, to which some are inclined in gestation. This sign, taken alone, can not be relied upon as diagnostic. It may be occasioned by various causes, and often accompanies the very same conditions attending menstrual suppression. Instances occur in every town and neighborhood where women have made elaborate preparations for confinement, only to be disappointed by finding they were suffering from some serious disease causing suppression. QUICKENING.--The involuntary movements of the child occur from the eighteenth to the twentieth week. Sometimes these motions begin as early as the third month, and then are a feeble fluttering only, causing disagreeable sensations of faintness and nausea. The “motion” of the child is regarded by women, especially if they have previously borne children, as an unfailing sign. But cases are common where the throbbing in a tumor, or the peristaltic action accompanying flatulence has been mistaken for fetal movements. Unless the _motion_ is very marked, quick, elastic and distinct, it alone cannot be relied upon as a diagnostic symptom. Taken together with other signs it aids both physician and patient to a positive conclusion. THE FETAL HEART BEAT.--The sign by which physicians can with certainty determine pregnancy is by noting the difference between the beating of the fetal and maternal hearts. The ordinary pulse of a woman is from 70 to 80 per minute, while that of the fetus is from 120 to 140. Auscultation through a stethoscope will reveal this fact, and thus give a certain diagnosis. If it is a throbbing or pulsating in a tumor it would be synchronous with the maternal cardiac action. This symptom is not of much value till after the fourth month. By that time, if a physician’s ear is educated to fine discriminations, he will never make a mistake in his diagnosis.