ITS CHEMICO-PHYSICAL AXD MORPHOLOGICAL PROPERTIES 



21 



the cells of a honeycomb, being in the form of very varying poly- 

 hedra ; they are separated from one another by the most delicate 

 lamellae of oil, which refract the light somewhat more strongly 

 than the watery liquid does. As a result of physical laws, only 

 three lamellae can touch at one 

 edge. Hence it appears in optical 

 section, that only three lines meet in 

 any one point. If before the for- 

 mation of the emulsion fine par- 

 ticles of lamp-black are distributed 

 throughout the oil, these collect at 

 the point of intersection. Finally, 

 the superficial layer is composed of a delicate froth, the frame- 

 work of which is arranged in a peculiar fashion, the partition 

 walls of oil, which touch the surface, being perpendicular to it, 

 and thus appearing parallel to one another in optical section. 

 Biitschli describes this as the alveolar layer (Fig. 3 alv.~). 



Butschli considers that the protoplasm of all plant and animal 

 cells (Figs. 4, 5) possesses a structure which is similar to this. 



FIG. 3. Optical section of the edge of 

 a drop of an emulsion made with olive 

 oil and salt; the alveolar layer (air.) is 

 very distinct, and relatively deep. ( x 

 1250 : after Biitgchli, PI. III., Fig. 4.) 



FIG. 4. FIG. 5. 



FIG. 4. Two living strands of plasma from a hair-cell of a Mtoliow. (x about 3,000 : 

 after Butschli, PI. II., Fig. 14.) 



FIG. 5. Web-like extension, very distinct in structure, from the pseudopodic net of a 

 Miliola from life, (x about 3.000 : after Butschli, PI. II., Fig. 5.) 



