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structures. And although in the brief account which I am about to 

 offer, I do not pretend to any entirely new observations, I yet may 

 claim for the subject this degree of importance, viz., that in a matter 

 of such great and acknowledged difficulty, and in one, moreover, in 

 which imagination has been too often allowed to be the substitute for 

 true observation in regard to many supposed facts, every addition 

 that can be made to our knowledge though it do but serve to confirm 

 already received doctrines, is valuable in itself on that account. Nor 

 do I know any better channel for communicating such knowledge, 

 and, if it be deemed worthy, of placing it on permanent record, and 

 thus making it generally useful, than that which our Society affords. 



The embryo which I am about to describe was expelled by abor- 

 tion three days ago. No information which I can procure from the 

 mother, affords any evidence as to the period of commencement of 

 pregnancy, because the ordinary data from which such calculations 

 are usually made, were not here present. No menstrual period 

 having occurred since the 5th of November last (four months and a 

 half from the present date). From the condition of the embryo, 

 however, I deem it to be of the fourth week of utero-gestation. 



The entire ovum weighed six drachms ; it measured two inches in 

 its longer, and one inch and a quarter in its shorter, diameter. All 

 the membranes were entire and perfectly distinct from each other. 

 The outermost or decidua vera exhibited the processes, termed by 

 Dr. Mongomery decidual cotyledons, in an unusually well-marked 

 degree. The cribriform markings on the inner or reverse surface 

 of the same membrane were equally distinct. The only point of 

 junction between this and the next membrane, or the decidua reflexa, 

 was at that part of the ovum which had lain over the cervix uteri, 

 and here it was reflected all round in a perfect circle on to the 

 chorion, in order to form the decidua reflexa. This, I may observe, 

 is not the most frequent point of reflection, which more commonly 

 is found towards one or other Fallopian tube, and consequently at the 

 upper part of the uterus. 



The observation of this latter fact is not unimportant for two 

 reasons. First, because it affords a probable explanation of the 

 cause of the ovum becoming aborted, for at whatever point the de- 

 cidua becomes reflected on to the ovum, there alone can the vessels 

 which connect the latter with the uterus enter. This is consequently 

 the most vascular part, the placenta is here formed, and if this more 

 vascular portion be implanted over or near the os uteri, hcemorrhage 

 is likely to occur, as in the present case ; the loss of blood leading 



