208 INFLAMMATION 



solid particles, such as bacteria and degenerating tissue elements. 

 These processes, which seem to indicate something approaching 

 independent volition on the part of the leucocytes, may, how- 

 ever, be well explained by application of known laws of chemis- 

 try and physics, without passing into the realms of the meta- 

 physical. This will be attempted under the heading of: 



AMEBOID MOTION AND PHAGOCYTOSIS 



The accumulation of leucocytes at a given point in the body 

 indicates that some means of communication must exist between 

 this point and the leucocytes in the circulating blood. No direct 

 communication by the nervous system or other structural meth- 

 od existing, the only possible explanation is that the communi- 

 cation is through the fluids of the body, and depends upon 

 changes in their chemical composition or physical condition. 

 As the latter generally depends upon the former, the communi- 

 cation is considered to be accomplished by chemical agencies, 

 and called chemotaxis. 



CHEMOTAXIS 



Changes in the chemical composition of a fluid have been 

 shown frequently to affect the motion of living organisms sus- 

 pended in it. One of the earliest observations w r as that of 

 Engelmann, 1 who noticed that Bacterium termo suspended in 

 water tended to accumulate about a bubble of oxygen in the 

 water. Pfeifer 2 discovered that the spermatozoids of certain 

 ferns were attracted powerfully by very dilute solutions of malic 

 acid, which is contained in the female sperm cell, indicating that 

 the migration of the sperm cells in the proper direction depends 

 on a chemical communication, and he proposed the term chemo- 

 taxis for this phenomenon. Strong solutions of malic acid, on 

 the other hand, repelled spermatozoids. Cane-sugar was found 

 to attract the spermatozoids of a certain foliaceous moss. In 

 the case of the malic acid, it seems to be the anion that produces 

 the effect, since salts of malic acid have exactly the same 

 property. 



StahPs 3 experiment with a large jelly-like plasmodium (Aethal- 

 ium septicum) growing on bark in wet places, has become class- 

 ical. He found that if the plasmodium was placed on a moist 

 surface, and near by was placed a drop of an infusion of oak 

 bark, the organism moved by the process of protoplasmic stream- 



1 Botanische Zeitung, 1881 (39), 441. 



2 Untersuch. aus dem Bot. Institut in Tiibingen, 1881-1888, Bd. 1 und 2. 



3 Botanische Zeitung, 1884 (42), 145 and 161. 



