[Footnote 8: Place a drop of the sediment upon a glass slide and allow it to dry. Mix thoroughly with a few particles of common salt and cover with a thin glass cover, under which allow two or three drops of glacial acetic acid to pass. Carefully warm the slide for a few seconds over a spirit-lamp, and when most of the acetic acid is evaporated, examine by the microscope. Hæmin crystals will be seen to crystallize out as the mixture cools.] In the matter of the presence or absence of blood-discs, it is to be remembered that these may be present at the moment the urine is passed, but disappear by subsequent solution if the urine happens to be alkaline or becomes so secondarily. It is an interesting fact, too, that colorless blood-corpuscles are often present intact, even when red discs are absent. While I have frequently examined urine sent me from the South in which the coloring matter of the blood and no corpuscles were present, only one of the cases coming under my own observations furnished urine of this character. The proportion of urea varies, and bears no evident relation to the condition itself. PATHOLOGY AND MORBID ANATOMY.--The pathology of malarial hæmaturia consists, as yet, chiefly of theoretical deductions. We can only conclude that the malarial poison acts upon the blood and blood-vessels, impairing the integrity of both. This goes so far occasionally as to produce an actual destruction of blood-discs, and always so alters the capillaries that they permit the transudation of blood-elements ordinarily retained. The morbid anatomy is scarcely more precisely defined. Ponfick[9] goes so far as to say that the exudation of hæmoglobulin is not possible without the concurrence of marked diffuse nephritis. Recently Lebedeff[10] has sought to investigate the more minute alterations of the kidney in hæmoglobin exudation, but without very definite results. These, however, on the whole, seem to confirm Ponfick's view as to the presence of an inflammatory process, as also do those of Litten[11] and Lassar.[12] [Footnote 9: "Ueber die Gemeingefährlichkeit der essbaren Morchel," _Virchow's Archiv_, Bd. lxxxviii. S. 476, 1882.] [Footnote 10: "Zur Kenntniss der feineren Veränderungen der Nieren bei der Hämoglobinausscheidung," _Virchow's Archiv_, Bd. xci. S. 267, Feb., 1883.] [Footnote 11: "Verhandl. des Vereins für innere Medicin," _Deut. Med. Wochenschr._, No. 52, Dec. 29, 1883.] [Footnote 12: _Ibid._, No. 1, Jan. 3, 1884.] DIAGNOSIS.--The diagnosis of this condition is not usually difficult. We have first to determine whether the hemorrhagic discharge is from the kidney rather than the bladder or ureters. The former is the case when tube-casts are found. But tube-casts are not always present even when the hemorrhage is from the kidneys. The absence of clots and of vesical irritation, and of pain in the course of the ureters, is characteristic of blood from the kidneys. Finally, all hæmoglobinurias are renal.