It is important to remember that chronic dysentery may result from bacillary as well as amoebic infections, although a chronic process is more a feature of amoebic dysentery. The muco-purulent stool of bacillary dysentery is more of a milky whiteness and flecked or streaked with blood or a very viscous bright blood-tinged mucus rather than the homogeneous, grayish brown, gelatinous mixture of disintegrated blood and mucus of the amoebic one. The odour is apt to be foetid in amoebic stools but rather albuminous with bacillary dysentery ones. =Laboratory Diagnosis.=—The chief point is to determine whether we are dealing with an amoebic or bacillary infection. While these two kinds of dysentery may coexist it is practical to consider a case in which amoebae with long, rapidly extruded, finger-like pseudopodia and containing red blood cells are found, as one of amoebic dysentery. A fresh specimen of the muco-purulent stool of bacillary dysentery shows, in addition to pus cells, numerous large, phagocytic cells, which may show vacuolation and strikingly resemble amoebae. Such cells never show motility but, under conditions of lowered temperature of specimen or from prolonged standing and beginning disintegration, the amoebae too fail to show motility. If mounted in Gram’s iodine solution these large cells show a much larger nucleus than that of amoebae and take the yellow staining of iodine more intensely. The best method, however, is to make a smear, fix it by heat and stain by Gram’s method or with Loeffler’s blue or dilute carbol fuchsin. These confusing cells stain easily and perfectly and in the Gram specimen we note the Gram-negative bacilli in the cytoplasm. Giemsa’s stain, with methyl alcohol fixation, or the usual Wright or Leishman technique answer equally well. On the other hand it is rather difficult to obtain satisfactorily stained amoebae in this way, it usually being necessary to fix moist thin smears of the stool with some bichloride fixative, as Zenker’s fluid, and then carry out the staining with haematoxylin. _The Stained Smear._—The presence of pus cells as well as endothelial cells in a stained smear of material from a bacillary dysentery stool is of value in differentiating from an amoebic stool smear in which pus cells are rarely seen. The amoebic dysentery smear gives more the picture of granular débris. We should always examine a stool as soon after it is passed as possible.