362 



PLATE X 



Fig. 1, a, b. Red blood corpuscles of Eana esculenta, iodine-alcohol, acid 

 hsematoxylin, daraar. Only the nuclei stained. 1, a, view of the 

 broad side. At o a small part of the surface and structure of the proto- 

 plasm is depicted. In the rest of the figure the equatorial optical 

 section is represented. 1, b, view of the narrow side, optical median 

 section. In both views the alveolar layer (ah) is very distinct, g, the 

 limit of the protoplasm towards the cavity of the blood corpuscle. In 

 the nucleus (n] the framework stained blue with the red chromatin 

 granules can be plainly recognised, p, pellicle. 



Fig. 2. Transverse section through an axis-cylinder, rather distorted in 

 outline, from the ischiadic of Lepus cuniculus. Picro-sulphuric-osmic 

 acid, iron-hrematoxylin, water, x 4000. The somewhat irregular 

 transverse section was chosen because it was extremely thin (at most 1 /*), 

 and hence showed the structure very plainly. 



Fig. 3. Small part of a living pseudopodium of Actinosphcerium eichhornii 

 Ehb. a, the axial thread, surrounded by the distinctly alveolar proto- 

 plasm, which contains numerous strongly refractile granules. 



Fig. 4. Foam prepared from olive oil and sodium chloride. An out- 

 stretched lamella of foam, made up of a single layer, which it was 

 possible to study in optical section. Unfortunately I have not taken 

 accurate note of the special conditions under which this lamella was 

 observed, for it is clear that it could only exist in this manner under 

 peculiar relations, and for a short time, since the foam in question was 

 quite fluid. 



Fig. 5, a-c. Very small droplets of olive oil, and which are obtained by 

 shaking up some oil with 1 per cent soda solution. The droplets are in 

 close apposition to one another. Focussed slightly below the horizontal 

 equatorial plane of the drops, so that the apparent network produced 

 by the diffraction circles which is stretched out between the droplets 

 is seen very plainly. Diaphragm drawn far down. In Fig. 5, a, a few 

 small drops lie apposed to a large one, of which only a part of the 

 edge is drawn. In Fig. 5, c, a number of minute droplets are similarly 

 closely apposed to the margin of a very large one, so that the relations 

 become rather peculiar. With reference to the interpretation of these 

 remarkable appearances compare the text, pp. 211 et seq. Zeiss Apochr. 

 2 mm., Oc. 18. 



