• In the former case, the limits of the disease are not well defined; in the latter, the peculiar characters are unmistakable ; but in both there is some specific relation betwaen the symptoms, and in order to constitute chlorosis this relation must be clearly made out.
Suppression of the menses under the name of amenorrhoea be longs especially to the diseases or disorders of the uterus. Any female may be anemic from some one of the causes already and, as a casual result of debility, the catamenia may be scanty or absent; but this ought not to be called chlorosis; neither should the name be given to amenorrhoea when there is no condition of anemia associated with it. But when, in a young person there is no distinct cause for the anemia, and when along with it, deficiency of the menstrual flux occurs early, and total suppression soon follows, or when suppression precedes anaemia, the classification seems legitimate and useful.
§ 4. Anwmic Blood-murmurs.—The diseases which we have just been considering are characterized by a deficiency of red • blood. When the condition is produced by a change in quality rather than quantity, when the red globules are diminished greatly out of proportion to the loss of other constituents of the blood, unnatural sounds are often to be heard with the stethoscope at various points in the course of the circulation; over the heart, the arteries, or the large veins, while there is but little obstruction to the current to account for their production. The subject must be again referred to in speaking of diseases of the heart and great vessels; but its importance seems to justify a few words here to point out to the student how he may make himself ac quainted, so far as possible, with the diagnosis of a "blood-sound." The essential point which must ever be borne in mind is, that all "bruits' whatever are produced chiefly in the blood itself, and not in the solid structures; they are supposed to depend on vibra tions among the particles, or globules; the sound is really quite independent of the nature of the disease in which it is heard, although modified by it as it causes alterations of form in the channels, or simply gives rise to changes in the qualities of the blood. Such vibrations may be produced in any fluid by placing some obstruction in the course of its movements, and much more readily in thin fluids than in those which are more tenacious. The aptitude for their production in disease therefore varies with the quality of the blood, and the change of their recurrence, with the condition of the solid structures. In a perfectly healthy con dition of the blood they can only be produced by changes of certain amount in the form and calibre,of the passages, or by counter-currents; in slight deviation from health, less important alterations will serve to throw the particles into vibration; in the more advanced forms of anemia, even the natural difficulties which it has to overcome in passing through channels of varying size is sufficient to produce the effect, which will be more or less marked in proportion to the force and rapidity of the circulation.
No such phenomena is observed in health, simply because a due proportion exists between the tenacity of the fluid and the form of its canal.
Bearing in mind these different elements in the production of the sound, it will be readily understood that no certain diagnosis of the nature of the disease can be formed from its tone or inten sity. Generally speaking those which are unaccompanied by structural change have a very decided character of softness; but this is by no means peculiar to murmurs of this class. On the other hand, in considering the locality in which it is heard, we have to remember that the true blood-sound is only secondarily dependent on local causes, because we know d priori that a very slight impediment is sufficient for its production ; and it is reason able to expect that, if any circumstance give rise to its presence, it will be heard most readily where the current is most superficial. Another consideration affecting its situation is, that when the blood is thus liable to be thrown into sonorous vibration, the sound is propagated in every direction, after it has flowed past any trifling obstacle, to a much greater extent than when healthy blood is forced into the same vibration by some more powerful cause. Accordingly, we find it very readily produced by slight pressure on a bloodvessel ; e. g., the carotid artery : again, in traversing the heart, the blood passes through channels of vary ing size, and it is churned and mixed together in the ventricles in such a way as would naturally lead to the production of "anaa mic murmurs," whether on the right or the left side : the pulmo nary artery is most superficial in the chest, and therefore the sound is more frequently heard there : but when the apex of the heart comes much forward, and its base is thrown back, the arte ries being deeply covered by long-structure, the murmurs may be best heard through its walls, and even towards its apex. In decided ana3mia, a blood-sound can also be heard in the veins; a little management in tilting over the stethoscope towards the patient's head, so as partially to impede the returning current throurth the jugular veins, will generally develop this venous hum. It differs from the arterial blood-sound in being continu ous, and not intermittent: its tone varies in different individuals; but the best geperal idea of its character may be obtained from the roaring of a large shell, applied to the ea,r ; it is called by the French " bruit de diable," from the sound of the humming-top ; but this is both louder and shriller. Both sounds may often be heard together in the neck, as pressure is made with the edge of the stethoscope next to the thorax, or the most distant from it- more firmly, so as to stop the venous current altogether—or more gently, so as merely to impede it. When the experiment is well performed, the short whiff of the arterial sound contrasts strik ingly with the prolonged continuous hum of the vein.