A modification of this pipette, in which a constriction or short length of capillary tube is introduced just below the plugged mouth (Fig. 13, b), will also be found extremely useful in the collection and storage of morbid exudations. A third form, where the capillary portion is about 4 or 5 cm. long and only forms a small fraction of the entire length of the pipette (Fig. 13, c), will also be found useful. ~"Blood" Pipettes~ (Fig 15).--Special pipettes for the collection of fairly large quantities of blood (as suggested by Pakes) should also be prepared. These are made from _soft_ glass tubing of 1 cm. bore, in a similar manner to the Pasteur pipettes, except that the point of the blowpipe flame must be used in order to obtain the sharp shoulder at either end of the central bulb. The terminal tubes must retain a diameter of at least 1 mm., in order to avoid capillary action during the collection of the fluid. [Illustration: FIG. 15.--Blood pipettes and hair-lip pin in a test-tube.] [Illustration: FIG. 16.--Blood-pipette in metal thermometer case.] For sterilisation and storage each pipette is placed inside a test-tube, resting on a wad of cotton-wool, and the tube plugged in the ordinary manner. As these tubes are used almost exclusively for blood work, it is usual to place a lance-headed hare-lip pin or a No. 9 flat Hagedorn needle inside the tube so that the entire outfit may be sterilised at one time. For the collection of small quantities of blood for agglutination reactions and the like, many prefer a short straight piece of narrow glass tubing drawn out at either extremity to almost capillary dimensions. Such pipettes, about 8 cm. in length over all, are most conveniently sterilized in ordinary metal thermometer cases (Fig. 16). ~Graduated Capillary Pipettes~ (Fig. 17).--These should also be made in the laboratory--from manometer tubing--of simple, convenient shape, and graduated by the aid of "standard" pipettes (in hundredths) to contain such quantities as 10, 50, and 90 c. mm., and carefully marked with a writing diamond. These, previously sterilised in large test-tubes, will be found extremely useful in preparing accurate percentage solutions, when only minute quantities of fluid are available. [Illustration: FIG. 17.--Capillary graduated pipettes.] ~Automatic ("Throttle") Pipettes.~--These ingenious pipettes, introduced by Wright, can easily be calibrated in the laboratory and are exceedingly useful for graduating small pipettes, for measuring small quantities of fluids, in preparing dilutions of serum for agglutination reactions, etc. They are usually made from the Capillary Pasteur pipettes (Fig. 13, a). The following description of the manufacture of a 5 c. mm. pipette will serve to show how the small automatic pipettes are calibrated. 1. Select a pipette the capillary portion of which is fairly roomy in bore and possesses regular even walls, and remove the cotton-wool plug from the open end.