^ ERYTHROCYTES 273 



A consistent picture is obtained if the filamentous protein frame is 

 thought of as stratified parallel to the surface and the meshes as 

 shallow, tangentially extended lenses, when the body of the frame- 

 work will exhibit layer birefringence. Under these circumstances, 

 certainly, no pores would be visible in the top view of the skin. The 

 impression received is that sieve-like images are artefacts and not 

 natural structures. This suspicion is strengthened when one examines 

 Jung's photographs (1942) of erythrocyte membranes denatured by 

 heat haemolysis. There are similar sieve images, with even larger pores. 



More recent electron micrographs of ghosts by Bessis and Bricka 

 (1949) and 2aCek and Rosenberg (1950) do not show any sieve pores, 

 but a coherent fine granulated structure. Without doubt the surface 

 of these membranes is formed by aggregated globular protein mole- 

 cules, which leave only small capillaries between each other. It is open 

 to discussion how the haemoglobin molecules with a diameter of 

 action of 74. 5 A can diffuse across such a membrane with the velocity 

 characteristic for haemolysis. Probably the texture of the hydrated 

 membrane is much looser in vivo than in the completely dried state 

 necessary for the electron microscopic observation. If the capillaries 

 in the membrane appear to be too narrow for haemoglobin, haemo- 

 lysis must locally destroy submicroscopic parts of the membrane 

 where the haemoglobin can freely escape. The electron microscopy 

 does not give evidence of any such mosaic structure of the erythrocyte 

 membrane, which has often been postulated for the understanding of 

 the complicated permeability phenomena (Ponder, 1948). 



Putting together what we know with fair certainty of the sub- 

 microscopic intrinsic structure of the erythrocyte membrane, we must 

 come to the conclusion that the stromatin has a coherent texture which 

 appears to be laminated, on account of the form birefringence. In the 

 dry state there are lens-shaped or flat submicroscopic spaces. The 

 lipids envelop the whole surface of the erythrocytes in a continuous 

 film. The quantity of lipid is too small for a protein-lipid layer body. 

 In the hydrated state the stromatin is considerably swollen and it is 

 likely that, in vivo, the spacious meshes of this dilute gel are filled 

 with haemoglobin, which assumes the special state of a solute in close 

 packing. 



This expose of the microstructure of erythrocytes demonstrates 

 impressively the fact that submicroscopic morphology cannot be 



