_Cessation of the menses._ One of the most remarkable changes produced by pregnancy, and one which most constantly appears, is the cessation of the menstrual discharge. From its occurring so uniformly and so soon after conception, it is generally used by women as the best means of reckoning the duration of their pregnancy: still, however, it is very far from being a certain sign, and never can be depended upon by itself in forming our diagnosis. It is well known how many causes produce suppression of the catamenia, independent of pregnancy; and, on the other hand, ample experience has shown that suppressed catamenia are by no means a necessary consequence of pregnancy. Although the fact has been contradicted by men of experience, still the regular appearance of the menses for the first few months of pregnancy is of such frequent occurrence as to place the matter beyond all doubt: in stating this, we do not allude to occasional discharges of blood from the vagina, but to regular periodical appearances of fluid distinctly bearing all the characters and peculiarities of the catamenia. This fact has been noticed so long ago, as by Mauriceau, who says, "I know a woman who had four or five living children, and who had with every child her menses from month to month, as at other times, only in a little less quantity, and was so till the sixth month, yet notwithstanding she was always brought to bed at her full time."[31] It is rare, however, to meet with the catamenia at so late a period, although cases do now and then occur where it lasts throughout pregnancy; more frequently it does not continue beyond the third or fourth month. The source of this discharge appears to be from the vessels of the upper part of the vagina[32] and from the cervix uteri;[33] the gradually shortening of the latter as pregnancy advances may be considered as the reason why, in the majority of instances, the discharge diminishes after the second or third month, and usually ceases by the fifth or sixth. Dr. Dewees supports the same opinion with some excellent observations which are worthy of attention. "We are" says he "acquainted with a number of women who habitually menstruate during pregnancy until a certain period, but when that time arrives it ceases: several of these menstruated until the second or third months, others longer, and two until the seventh month; the last two were mother and daughter. We are certain there was no mistake in all the cases to which we now make reference. First, they (the menses) were regular in their returns, not suffering the slightest derangement from the impregnated condition of the uterus; 2. they employ from two to five days for their completion; 3. that the evacuation differed in no respect from the discharge in ordinary, except that they did not think it so abundant; 4. there were no coagula in any one of these discharges, consequently it could not be common blood of hæmorrhage; 5. in the two protracted cases,