pipettes is divided into centimetres. The blood is filled into the pipettes up to the fifth division, and the column of blood is aspirated some little distance up the tube in order to obviate any desiccation of the blood at the orifice. The tubes are easily cleaned by means of a fine wire. They are then washed out successively with distilled water, alcohol, and ether. When the ether evaporates the tubes are warmed in the hand or in an incubator and are then ready for use. In addition to these

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... dinary coagulation tubes Mr. Dean has, at Professor Wright's suggestion, made tubes provided with a mixing chamber. By employing these latter it is possible not only to study the effects of various additions upon the coagulability of a particular blood but also to repeat at any moment the classical experiments in connexion with blood coagulation. For this purpose it is only necessary to fill an aliquot part-say a sixth of the tubewith the fluid whose influence on coagulation it is desired to elicit. Into the tubes thus primed a column of blood of the usual length is introduced. Mixture of the fluid with the blood is effected by aspirating the contents of the tube into the mixing chamber and then immediately blowing them down in an unbroken column into the stem of the pipette. The coagulation time obtained with the mixed blood is, of course, compared with that elicited for the unmixed blood. The coagulation-inhibiting properties of decalcifying substances (such as soluble oxalates and citrates), or of additions of neutral salts, or of leech extract can readily be demonstrated by this method. To do this it is only necessary to prime the tubes (say up to the first division) with a 1 per cent. solution of oxalate of soda, a from 3 to 5 per cent. solution of citrate of soda, a from 20 to 25 per cent. solution of sodium chloride or magnesium sulphate, or, lastly, a decoction of a leech which has been sliced up after it has been killed by alcohol.