Cohnheim's experiments on inflammation and Mel- 

 schnikofFs phagocyte theory have made investi- 

 gations into the chemotaxis of monocellular or- 

 ganisms of the greatest importance to general patho- 

 logy. From this point of view the following communi- 

 cation may perhaps be of some interest. 



A phenomenon which till now has escaped obser- 

 vation is the negative chemotactic action that dead 

 infusoria have on living ones. I observed this fact for 

 the first time when, on repeating Mendelsohn's experi- 

 ments on thermotropism, I happened to kill a few 

 Oxytrichae by overheating. 



a. The readiest way of making the experiment is by 

 taking a drop containing plenty of infusoria of the 

 same species and placing it under a lamella. If its 

 surface then is touched for a moment with a platina 

 needle or a glass-rod intensely heated, a more or 

 less considerable number of infusoria will be killed. 

 The live individuals will stop as soon as they ap- 

 proach the dead infusoria, often even at a very great 

 distance, and withdraw so as to leave a circular 

 space into which no living organism penetrates. 

 A very vivid illustration of the occurrence may be 

 had by drawing the dead bodies by means of a 

 camera lucida and by following afterwards the mo- 

 vements of the living individuals exactly marking, at 



