358 Dr. A. E. Wright and Capt. S. R. Douglas. [Sept. 1, 



The films thus obtained are stained by Leishman's* modification 

 of Romanovski's stain, and are subjected to examination under an 

 immersion lens. By enumerating the bacteria ingested in a number of 

 polynuclear white blood corpuscles and dividing, an average is obtained. 

 This average is taken as the measure of the phagocytic power of 

 the blood. It is compared, when comparative experiments are made, 

 with the phagocytic power of a normal blood. 



We have modified this method for our purposes (a) by conducting 

 the phagocytosis in capillary tubes, making afterwards film prepara- 

 tions in the ordinary way ; (b) by decalcifying the blood with citrate 

 of soda, thus avoiding the complications introduced by blood coagula- 

 tion, and making it possible to separate the white corpuscles from the 

 blood fluids by centrifugalisation, decantation and washing. 



Three different procedures, varying only in details, were employed in 

 our experiments. 



Procedure No. 1, Employed where Nothing more than a Comparison between 

 Moods from Different Sources or Bloods Subjected to Different Conditions 

 is Required. 



Having provided ourselves with a simple capillary pipette, furnished 

 with a rubber teat and a pencil mark on the stem, we aspirate into 

 the stem of the pipette dividing off by bubbles of air in accordance 

 with the procedure introduced by one of us one volume of blood from 

 the finger, one volume of a 1-per-cent. solution of citrate of soda in 

 physiological salt solution, and one volume of a bacterialf suspension 

 made by shaking up a 24-hour agar culture in physiological salt solu- 

 tion and centrifugalising so as to remove any bacterial clumps. We mix 

 together the three equal volumes of blood, bacterial suspension and 

 citrate of soda solution, by blowing these out upon a clean slide and 

 re-aspirating several times in succession. Mixture completed, an 

 aliquot portion of the mixed fluids, such as suffices for our purposes, 

 is drawn up into the capillary stem, and the orifice of the capillary 

 tube is sealed in the flame. This done, the pipette is placed either in 

 an incubator standing at 37 C. or in a vessel of water kept at this 

 temperature. 



After the lapse of 15 minutes we break off the extremity of the 

 pipette, carefully mix the contents so as to get an average sample, 

 and proceed to make films, and then to stain them by Leishman's dye. 



1 Brit, Med. Journ./ 1901. 



f This bacterial suspension may conveniently contain about 10,000,000,000 

 bacteria in the cubic centimetre. The number may be readily adjusted by 

 the help of the method of enumeration under the microscope described by one of 

 us in the ' Lancet,' July 5, 1902. 



