156 THE EXCITATION OF AMCEBOID MOVEMENTS 



of fallacy arising in the technique of the "opsonic 

 index," if it is carelessly carried out, because in that 

 technique fixed films are usually employed. 



The possibility of foreign substances being crushed 

 into cells during the preparation of fixed films is also 

 the reason, we think, for the common, fallacious 

 supposition which has already been mentioned that 

 the blood-platelets are the extruded nuclei of red 

 cells, for in the preparation of fixed films platelets are 

 crushed into red cells, to which they often adhere, and 

 after fixation they appear as if they were emerging 

 from them; an artefact never seen with the jelly 

 method. 



In concluding this chapter it should be mentioned 

 that Professor Osier, many years ago, pointed out 

 that certain alkaloids excited amoeboid movements 

 in leucocytes, although this fact was not known to 

 me when the effects of atropine mixed with the jelly- 

 film were first tried. 



As will be shown later, alkaloids have a far more 

 important action on cells than merely exciting amoe- 

 boid movements, for they greatly augment the action 

 of the exciters of reproduction. 



