978 OF GENERATION. 



tied by the extravasation of fluid, probably consequent upon the force used in inject- 

 ing the vessels. Moreover, the different size of the blood-corpuscles in the foetus 

 and in the parent ( 149) shows the non-existence of any such communication. 



983. The formation of the Placenta, in the manner just described, commences 

 in the latter part of the second month ; during the third, the organ acquires its 

 proper character ; and it subsequently goes on increasing in accordance with the 

 growth of the ovum. Towards the end of the term of gestation, however, it 

 becomes more dense and less vascular ; owing, it would seem, to the obliteration 

 of several of the minuter vessels, which are converted into hard fibrous filaments. 

 The vessels of the uterus undergo great enlargement throughout, but especially 

 at the part to which the placenta is attached; and the blood in moving through 

 them produces a peculiar murmur, which is usually distinctly audible at an early 

 period of pregnancy, and may be regarded (when due care is taken to avoid 

 sources of fallacy) as one of its most unequivocal positive signs. The " pla- 

 cental bruit" is thus described by Dr. Montgomery: 1 "The characters of this 

 phenomenon are, a low murmuring or somewhat cooing sound, resembling that 

 made by blowing gently over the lip of a wide-mouthed phial, and accompanied 

 by a slight rushing noise, but without any sensation of impulse. The sound is, 

 in its return, exactly synchronous with the pulse of the mother at the time of 

 examination ; and varies, in the frequency of its repetitions, with any accidental 

 variation which may occur in the maternal circulation. Its situation does not 

 vary during the course of the same pregnancy ; but in whatever region of the 

 uterus it is first heard, it will in future be found, if recognized at all for it is 

 liable to intermissions at least, we shall occasionally be unable to hear it where 

 we have already heard it a short time before, and where we shall shortly again 

 recognize it. According to my experience, it will be most frequently heard 

 about the situation of the Fallopian tube of the right side ; but it may be detected 

 in any of the lateral or anterior parts of the uterus." That the cause of this 

 sound exists in the uterus itself, is distinctly proved by the fact, that it has 

 been heard when that organ was so completely anteverted, that the fundus hung 

 down between the patient's thighs. A sound so much resembling this as to be 

 scarcely distinguishable from it may be occasioned, however, by a cause of a 

 very different nature namely, an abdominal tumor, pressing upon the aorta, 

 iliac arteries, or enlarged vessels of its own ; and, in doubtful cases, it is neces- 

 sary to give full weight to the possibility of such an explanation. The sound 

 may be imitated at any time, by pressing the stethoscope on the iliac arteries. 

 The placental bruit has been not unfrequently heard in the eleventh week; but 

 it cannot generally be detected before the fourth month, when the fundus uteri 

 rises above the anterior wall of the pelvis. 



984. The amount of the peculiar tissue of the Uterus ( 305) greatly 

 increases during pregnancy. At the same time, the Mammary gland and its 

 appendages undergo a fuller development ; and from this a valuable, but not 

 unequivocal, indication of pregnancy may be drawn. Occasional shooting 

 pains in the MammaB are not unfrequently experienced within a short period 

 after conception ; and more continued tenderness is also not unusual. A sense 

 of distension is very commonly experienced at about the end of the second 

 month; and from that time a distinct "knottiness" usually begins to present 

 itself, increasing with the advance of pregnancy. In many instances, kowever, 

 these mammary sympathies are entirely absent ; and they may be simulated by 

 changes that take place in consequence of various affections of the uterus. A 

 change of color in the areola is a very common, but not an invariable, occur- 

 rence in the early months of pregnancy ; but another sign is afforded by the 

 areola and nipple, which is of more value because more constant namely, a 



1 " Signs of Pregnancy," p. 121. 



