74 THE CELL 



the specific gravity of which is slightly greater than that of 

 water, and then, by means of a fine capillary tube, he caused a 

 drop of 2 per cent, solution of soda to approach the globule 

 of oil. This latter then exhibited changes in shape, which are 

 similar to those observed with the microscope in certain Amoebae. 

 The explanation of this is that the soda solution gradually 

 spreads itself out over the surface of the oil, forming a soap. 



Quincke is of opinion that the protoplasmic movements are 

 analogous to these. In the plasmolysis of plant cells, the proto- 

 plasm frequently breaks up into two or more balls, which 

 spread themselves out, and then either re-unite, or remain 

 separated from one another by an even surface, just as two 

 soap bubbles of equal size which are placed in contact may 

 touch each other, without uniting. In consequence of these 

 appearances he is of opinion that, considering the physical pro- 

 perties of delicate solid or fluid lamellae, the protoplasm must 

 be surrounded by a very delicate fluid membrane, just as in 

 the soap bubble the air is enclosed in a thin skin layer of 

 soap solution. " The substance of the membrane surrounding 

 the protoplasm," as Quincke proceeds to state, " must be a 

 fluid which forms drops in water. Since of all the substances 

 known in nature oil is the only one which possesses this pro- 

 perty, the membrane must consist of an oil, that is to say of a fluid 

 fat. The thickness of this layer may be most minute, less than 

 '0001 mm., and hence it is not perceptible even with the micro- 

 scope." Through the action of the albumen upon this oil, a 

 substance is produced upon the areas of contact, which is soluble 

 in water, and spreads itself out just like the soap produced 

 by the combination of soda and oil. Hence it is called albuminous 

 soap. 



Thus Quincke considers the cause of the protoplasmic move- 

 ments to be a periodic spreading out of albuminous soap upon the 

 inner surface of the envelope of oil surrounding the protoplasm. 

 This soap, in being continually re-formed on the area of contact 

 as fast as it is dissolved and diffused throughout the surrounding 

 fluid, remains constant in quantity; thus, since the presence of 

 oxygen is necessary in this chemical process, the fact is explained, 

 that, in its absence, the protoplasmic movements are arrested, and 

 similarly their cessation at extreme temperatures may be ascribed 

 to chemico-physical conditions. 



Biitschli, being stimulated by these investigations of Quincke, 



