KINETIC JELLY 139 



will kill it, and therefore all the leucocytes in the 

 specimen slowly begin to retract their pseudopodia, 

 for leucocytes endeavour to resume their spherical shape 

 before death. The long snake-like processes can be 

 seen to shrink back gradually into the cells (figs. 7,8), 

 until in most cases they are completely retracted 

 (fig. 9). Occasionally, however, a constriction appears 

 in a pseudopodium where it arises from the cell-wall 

 (fig. 26), and separation has actually been seen to take 

 place; the separated portion, often containing a few 

 cell-granules, will now resemble a blood-platelet. Soon 

 after the pseudopodia have been retracted the cell dies, 

 and either bursts or becomes achromatic. 



If the jelly has been properly prepared the whole 

 phenomenon of excitation of amoeboid movements will 

 be over in about twenty-five minutes or so. The action 

 of this kinetic jelly is instructive, for it affords 

 another example of the diffusion of substances into the 

 cells, and of the accuracy of the equation used in its 

 preparation in relation to this diffusion. The way of 

 making the jelly has been described, and it must be 

 remembered that it contains 0.7 cc. of a 1-per-cent 

 solution of atropine sulphate. Now, this is a salt, and 

 it delays diffusion; hence its unit must be ascertained 

 before the correct equation can be made for this jelly. 

 The unit of atropine sulphate (as found by experiment) 

 is .013 gramme, and therefore since the jelly contains 

 . 7 cc. of a 1-per-cent solution, it must contain . 5 of 

 1 unit, which may now be added to the equation among 

 the other salts w r hich are minus factors. We may now 



