James Campbell Todd

“ Cryoscopy, determination of the freezing-point, depends upon the principle that the freezing-point of a fluid is depressed in proportion to the number of molecules in solution. To have any value, the freezing-point of the urine must be compared with that of the blood, since it is not so much the number of molecules contained in the urine as the number which the kidney has failed to carry off and has left in the blood, that indicates its insufficiency. ”

“ The reaction of human milk is slightly alkaline; of cow's, neutral or slightly acid. The specific gravity of each is about 1.028 to 1.032. Human milk is sterile when secreted, but derives a few bacteria from the lacteal ducts. Cow's milk, as usually sold, contains large numbers of bacteria. Microscopically, human milk is a fairly homogeneous emulsion of fat, and is practically destitute of cellular elements. ”

“ When a malarious person is bitten by a mosquito, the gametes are taken with the blood into its stomach. Here a flagellum from the male unites with the female, which soon thereafter becomes encysted in the wall of the intestine. After a time it ruptures, liberating many minute rods, or sporozoites, which have formed within it. These migrate to the salivary glands, and are carried into the blood of the person whom the mosquito bites. Here they enter red corpuscles as young malarial parasites, and the majority pass through the asexual cycle just described. ”

“ Trichiniasis is generally accompanied by a marked eosinophilia. The diagnosis is made by teasing out upon a slide a bit of muscle, obtained preferably from the outer head of the gastrocnemius, the insertion of the deltoid, or the lower portion of the biceps. The coiled embryos can easily be seen with a two-thirds objective (Fig. 108) .
(5) Uncinaria.—The two varieties of this worm, Uncinaria duodenalis and Uncinaria Americana, are among the more harmful of the animal parasites. They inhabit the small intestine, usually in great numbers, and commonly produce a severe and often fatal anemia. ”

“ Wright's stain the nucleus is less deeply colored than that of the lymphocyte, while the cytoplasm is very pale blue or colorless, and sometimes contains a few reddish granules. The size of the cell, the width of the zone of cytoplasm, and the depth of color of the nucleus are the points to be considered in distinguishing between large mononuclears and lymphocytes. When large forms of the lymphocyte are present, the distinction is often difficult or impossible. It is then advisable to count the two cells together as lymphocytes. ”

“ Small, round, or polyhedral cells are about the size of pus-corpuscles, or a little larger, with a single round nucleus. Such cells may come from the deeper layers of any part of the urinary tract. They are uncommon in normal urine. When they are dark in color, very granular, and contain a comparatively large nucleus, they probably come from the renal tubules, but their origin in the kidney is not proved unless they are found embedded in casts. Renal cells are abundant in parenchymatous nephritis, especially the acute form. ”

“ Micro-organisms are always present in large numbers. Among these is Leptothrix buccalis (Fig. 121) , which is especially abundant in the crypts of the tonsils and the [p. 271] tartar of the teeth. The whitish patches of pharyngomycosis leptothrica are largely composed of these fungi. They are slender, segmented threads, which generally, but not always, stain violet with Lugol's solution, and are readily seen with a one-sixth objective. At times they are observed in the sputum and stomach fluid. In the former they might be mistaken for elastic fibers; in the latter, for Boas-Oppler bacilli. ”

“ Lymphocytes are formed in the lymphoid tissues, including that of the bone-marrow. They constitute, normally, 20 to 30 per cent. of all leukocytes, or about 1000 to 3000 per c.mm. of blood. They are more abundant in the blood of children.
The percentage of lymphocytes is usually moderately increased in those conditions which give leukopenia, especially typhoid fever, chlorosis, pernicious anemia, and many debilitated conditions. A marked increase, accompanied by an increase in the total leukocyte count, is seen in pertussis and lymphatic leukemia. ”

“ It is so heavy that one is apt to forget that parts of it are fragile. It seems unnecessary to say that when there is unusual resistance to any manipulation, force should never be used to overcome it until its cause has first been sought; and yet it is no uncommon thing to see students, and even graduates, push a high power objective against a microscopic preparation with such force as to break not only the cover-glass, but even a heavy slide.
It is most convenient to carry a microscope with the fingers grasping the pillar and the arm which holds the tube ”

“ Renal Calculus.—The urine is usually somewhat concentrated, with high color and strongly acid reaction. Small amounts of albumin and a few casts may be present as a result of kidney irritation. Blood is frequently present, especially in the daytime and after severe exercise. Crystals of the substance composing the calculus—uric [p. 136] acid, calcium oxalate, cystin—may often be found. The presence of a calculus generally produces pyelitis, and variable amounts of pus then appear, the urine remaining acid in reaction. ”

“ They might be mistaken by the inexperienced for red blood-corpuscles, fat-droplets, or the spheric crystals of calcium oxalate, but are distinguished by the facts that they are not of uniform size; that they tend to adhere in short chains; that small buds may often be seen adhering to the larger cells; and that they do not give the hemoglobin test, are not stained by osmic acid or Sudan but are colored brown by Lugol's solution, and are insoluble in acids and alkalis. Yeast-cells multiply rapidly in diabetic urine, and may reach the bladder and multiply there. ”

“ In films stained by Gabbet's method tubercle bacilli, if present, will be seen as slender red rods upon a blue background of mucus and cells (Plate II, Fig. 2) . They average 3 to 4 μ in length—about one-half the diameter of a red blood-corpuscle. Beginners must be warned against mistaking the edges of cells, or particles which have retained the red stain, for bacilli. The appearance of the bacilli is almost always typical, and if there seems room for doubt, the structure in question is probably not a tubercle bacillus. They may lie singly or in groups. ”

“ A study of blood bacteriology is useful, but is hardly practicable for the practitioner. Most bacteria can be detected only by culture methods. The spirillum of relapsing fever can be identified by the method for the malarial parasite in fresh blood. The blood must be taken during a paroxysm. The organism is an actively motile spiral thread, about four times the diameter of a red corpuscle in length. The movements which its active motion causes among the corpuscles render it conspicuous. ”

“ Its nucleus is large, stains rather palely, has a delicate chromatin network, and often shows evidences of degeneration (karyorrhexis, etc.) . In ordinary work, however, it is safer to base the distinction upon size than upon structure. Any nucleated red cell, but especially the megaloblast, may exhibit polychromatophilia.
Normally, erythroblasts are present only in the blood of the fetus and of very young infants. Pathologically, normoblasts occur in severe symptomatic anemia, leukemia, and pernicious anemia. ”

“ In acute and chronic parenchymatous nephritis the quantity is usually very large. In chronic interstitial nephritis it is small—frequently no more than a trace. It is small in cloudy swelling from toxins and drugs, and variable in renal tuberculosis and neoplasms. In amyloid disease of the kidney the quantity is usually small, and serum-globulin may be present in especially large proportion, or even alone. Roughly distinctive of serum-globulin is the appearance of an opalescent cloud when a few drops of the urine are dropped into a glass of distilled water. ”

“ Examine with a low power to see that the cells are evenly distributed. Count with the two-thirds objective and a high eye-piece, or with the long-focus one-sixth and a low eye-piece. [p. 164] A one-fourth objective will be found very satisfactory for this purpose.
With the ordinary ruling of the disc, count all the leukocytes in the large square, multiply by 10 to find the number in 1 c.mm. of diluted blood, and by the dilution to find the number per c.mm. of undiluted blood. In every case at least 100 leukocytes must be counted as a basis for calculation, and it is much better to count 500. ”

“ In films which are properly stained with Wright's fluid the young organisms are small, round, ring-like or irregular, sky-blue bodies, each with a very small, sharply defined, reddish-purple chromatin mass. Many structures—deposits of stain, dirt, blood-plaques lying upon red cells, etc.—may simulate them, but should not deceive one who looks carefully for both the blue cytoplasm and the reddish-purple chromatin. ”

“ Pus contains much granular débris and numerous more or less degenerated cells, the great majority being polymorphonuclear leukocytes—so-called "pus-corpuscles." Eosinophilic leukocytes are common in gonorrheal pus and in asthmatic sputum. Examination of pus is directed chiefly to detection of bacteria.
When very few bacteria are present, culture methods must be resorted to, but such methods do not come within the scope of this work. When considerable numbers are present, they can be detected and often identified in cover-glass smears. ”

“ Acetone is present in considerable amounts in many cases of diabetes mellitus, and is always present in severe [p. 84] cases. Its amount is a better indication of the severity of the disease than is the amount of sugar. A progressive increase is a grave prognostic sign.
Detection of Acetone.—The urine may be tested directly, but it is best to distil it after adding a little phosphoric or hydrochloric acid to prevent foaming, and to test the first few cubic centimeters of distillate. ”

“ The rare and rapidly fatal anemia which has been described under the name of aplastic anemia is probably a variety of pernicious anemia. Absence of any attempt at blood regeneration explains the marked difference in the blood picture. Red corpuscles and hemoglobin are rapidly diminished to an extreme degree. The color index is normal or low. The leukocyte count is normal or low, with relative increase of lymphocytes. Stained smears show only slight variations in size, shape, and staining properties of the red cells. ”

“ Motility is impaired to some extent in chronic gastritis. It is especially deficient in dilatation of the stomach due to atony of the gastric wall or to pyloric obstruction, either benign or malignant. It is increased in most conditions with hyperchlorhydria.
The best evidence of deficient motor power is the detection of food in the stomach at a time when it should be empty, e.g., before breakfast in the morning. When more than 60 c.c. of fluid are obtained with the tube one hour after a Ewald breakfast, deficient motility may be inferred. ”