METHODS 23 



conditions. These conditions have been designated 

 " the experimental ten minutes," and they also 

 will be found explained in detail in former 

 publications. 



In order to test for excitation of amoeboid 

 movements (kinetic action) the same rule applies, 

 with the exception that the slides are kept at the 

 room temperature, because white blood-cells seem 

 to show more exaggerated amoeboid movements 

 in response to kinetics at a lower temperature 

 than they do at blood heat. 



When testing a substance to see if it has kinetic 

 action several specimens were made from the jelly 

 which contained the substance, and control speci- 

 mens were made simultaneously which contained 

 no such substance, but only the usual salts ; the 

 two slides being kept together. Unless more than 

 50 per cent, of the white cells in the test speci- 

 mens showed marked exaggerated movements 

 with extrusion and retraction of long pseudopodia 

 in definite contrast to the control specimens, the 

 substance was considered not to be effective. In 

 a similar way, when testing for auxetic action, 

 unless a large number of lymphocytes showed 

 well-marked division figures at the end of the 

 ten minutes, the substance in the jelly was con- 

 sidered not to be effective. With experience these 

 figures can easily be recognised, even if no stain 

 is employed and the cells are colourless. The 

 cells adopt an appearance quite unlike resting 

 cells (a fact which a control specimen will readily 

 demonstrate), and in many instances the arrange- 

 ment of the chromosomes (frequently contained 

 in finger-like processes of cytoplasm), or even 



