THE VITAL PROPERTIES OF THE CELL 75 



has undertaken some interesting experiments based on the assump- 

 tion of his foam or emulsion theory of protoplasm, and these, as it 

 appears to him, throw light upon the cause of the protoplasmic 

 movements. He prepared frothy structures of oil in various ways. 

 The most delicate and instructive masses were obtained by mix- 

 ing a few drops of olive oil, which had been kept for some time 

 in a warm chamber, with some finely powdered K C0 3 , until a 

 viscous mass was produced ; a small drop of this mixture was 

 then introduced into water. The emulsion which is produced in 

 this manner is milky white in appearance, and consists of minute 

 vacuoles, filled with the solution of soap, which is formed at the 

 same time : it may be cleared by adding to it a few drops of dilute 

 glycerine. By this means active streaming movements are pro- 

 duced, which, in a successful preparation, last for at least six days, 

 and which are certainly surprisingly like the protoplasmic move- 

 ments of an Amoeba. "From one place on the edge the current 

 flows through the axis of the drop ; it then streams away from the 

 edge down both sides, in order to unite again, gradually to form 

 the axial current again. Here and there a blunt process is pro- 

 truded and withdrawn, and so on ; indeed, individual drops may 

 exhibit fairly active locomotive powers for a time." Butschli, in 

 accordance with Quincke's experiments, explains these phenomena 

 of movement in the following manner : " On some place on the 

 surface some of the delicate chambers of the froth structure burst, 

 and thus the soap solution at this region is able to reach the sur- 

 face of the drop, which is composed of a very thin lamella of oil. 

 The necessary consequence of this is a diminution of surface- 

 tension at this spot, and hence a slight bulging and out-streaming 

 occur. Both of these induce a flow of foam-substance from the 

 interior to this spot. A few more meshes may be broken down 

 by this current, and so on, the result being that a streaming, once 

 induced, is persistent unless considerable obstacles present them- 

 selves." Butschli is quite convinced that the streaming move- 

 ments seen in these saponified fat drops are identical in all 

 essentials with amoeboid protoplasmic movements. 



These experiments of Quincke and Butschli are of the greatest 

 interest, for they prove that very complex phenomena of move- 

 ment may be induced by means of comparatively simple methods. 

 On the other hand, various objections may be raised against their 

 deduction, that in protoplasmic movements similar processes 

 occur. Even the hypothesis, that the protoplasmic substance is 



