1598 Journal of Applied Microscopy 



may extend in several directions at once ; at times the drop may divide, — as also 

 happens in Amoeba ! Altogether, the drop of clove oil imitates with some degree 

 of closeness the behavior of Amoeba. The movements are of course due to local 

 alterations in the surface tension of the drop of clove oil, owing to its irregular 

 mixing with the alcohol. 



As to the details of the experiment, the following may be said : 



Pure clove oil is used. For the glycerine-alcohol mixture, use either three 

 parts glycerine to one part 96 per cent, alcohol, or two parts glycerine to one part 

 70 per cent, alcohol. If the movements are later found to be too rapid and 

 violent, add some water, or more glycerine. If the movements are too slow, add 

 a little more alcohol to the mixture. 



Proceed as follows : Place upon a slide two fine glass rods, for supporting 

 the cover-glass. These may very conveniently be fastened to the slide, at a 

 proper distance apart, with balsam. Place some of the glycerine-alcohol mixture 

 on the slide, and cover with a cover-glass. Draw an ordinary medicine dropper 

 out to a fine capillary point. Take up some of the clove oil with this, insert the 

 point beneath the cover-glass, and inject a drop of the clove oil into the glycerine 

 and alcohol. It will usually begin at once to change form and move about. 



The thickness of the glass rods supporting the cover-glass is of importance ; 

 if these are too thick, the movements will not be marked. Experiments should 

 be made with rods of various thicknesses. 



I have found this method of imitating protoplasmic movements much simpler 

 than the preparation of Biitschli's emulsion of potassium carbonate and old olive 

 oil, which is often difficult to prepare unless olive oil of exactly the right degree 

 of rancidity is at hand. 



2. Control of the Direction of Movetnetit. With the drop of clove oil prepared 

 as above, various methods can be illustrated by which the direction of movement 

 might be controlled, in a mass which moves through changes in its surface ten- 

 sion. That a local chemical change taking place within the Amoeba (producing 

 thus a new chemical substance in a certain area) might cause the formation of a 

 pseudopodium, and movement in a certain direction, may be illustrated by intro- 

 ducing some chemically different substance into a certain region of the drop of 

 clove oil. A very satisfactory method is to inject a little 70 per cent, alcohol 

 into the drop near one side. Take up a small drop of the alcohol in a pipette 

 drawn to a very fine point ; introduce this beneath the cover-glass and into 

 the drop, and press out a very little of the alcohol into the drop, removing the 

 pipette at once. If this is skilfully done, and not too much alcohol is added, the 

 drop will at once send out a " pseudopodium " on the side nearest which the 

 alcohol was introduced, and often follows this up by moving in that direction. 

 Of course if the alcohol (or any substance having less surface tension than the 

 clove oil) could have been produced through a chemical change within the clove 

 oil, the resulting movement would be the same. 



Some practice is necessary to perform this experiment successfully. It is 

 particularly important to use a freshly mounted drop of clove oil, which still 

 shows some " spontaneous " movement. After a time the drop seems to become 

 covered with a sort of incrustation which prevents its free movement. It is also 



