410 APPENDIX II 



the end remote from the mark 4. The lower meniscus standing at 

 4 where the tube has been cut, and the upper meniscus standing at 

 12, blood from the finger of the persons whose corpuscles are going 

 to be tested is added until the upper meniscus stands at 13 (i.e. the 

 mixture equals 1-9). Mixture is ensured as before and the tube 

 sealed. It will be seen that although the tube contains the plasma 

 of both persons the corpuscles are bathed in a solution containing 

 four times as much plasma of the first person as of the second. A 

 series of tubes may thus be made. 



Appliance to ensure continual mixture and to prevent the cor- 

 puscles from adlierincj to the glass.- If a capillary tube prepared 

 in the way which has been described is laid on a flat surface, the 

 corpuscles will soon gravitate to the most dependent side and will 

 ultimately adhere to the glass. The following appliance prevents 

 this. By means of a simple clockwork movement a split drum is 

 made to revolve once in about three minutes. The drum is so 

 adapted thaT the mouth of a long test-tube (having a diameter of 

 one centimetre and the cavity of which is lined with a roll of blot- 

 ting paper) fits accurately on to it and revolves with it. The 

 apparatus is so arranged that the tube is horizontal and is of such 

 a size that it can be placed in the incubator if necessary. The 

 capillary tubes inserted into the test-tube are continually tumbling 

 over each other by gravity as the test-tube revolves, and in so doing 

 revolve themselves. The blood-cells in their turn are continually 

 gravitating in different directions through the citrated plasmata. 

 It has been found that this device prevents them adhering to the 

 glass and ensures them being evenly distributed through the 

 citrated plasmata provided the ends of the capillary tubes are not 

 bent over when sealed. This apparatus also insures all capillary 

 tubes being subjected to the same conditions of temperature. 



Procedure for measuring the lives of tlie leucocytes contained in 

 the tubes. Samples of the contents of the capillary tubes are 

 examined on stimulating agar by the method already described. 

 If all the cells are alive the tubes are resealed and returned to the 

 revolving apparatus to be examined later, and so on. By this 

 means the percentage of living and dead cells in a tube can be 



