541 



Wilhelm Menke 



polarly -built thylakoid membranes which are oriented enantiomerically to 

 each other. 



The next point to be clarified was the manner in which the individual thyla- 

 koid membranes are linked to the thylakoid, i. e. whether the^rotein layer 

 or the lipid layer forms the external boundary of the thylakoid'^'^'. This ques- 

 tion could be answered since it proved possible to obtain films of oriented 

 chloroplasts in which no noticeable disorganization of lipids had taken place, 

 by drying a chloroplast suspension onto glass plates. In such films the thyla- 

 koids are situated approximately parallel to the film-plane. Fronm the point 

 of view of polarization optics the whole film behaves like an uniaxial double - 

 refracting crystal plate. The optical axis emerges vertically to the film- 

 plane. When the support is removed, such films will, if they contain a cer- 

 tain amount of water, roll up into little tubes. These tubes were found serv- 

 iceable for further investigations. They produced a series of interferences 

 (Plates 1, 2) the first order of which, d^ending on the degree of drying, 

 corresponds to Bragg values of 152-166A. The interference of the first order 

 is very weak, the second order the strongest. This series of interferences 

 is caused by a period parallel to the film normal. Moreover, all the prepar- 

 ations display a faint, diffuse ring at 36.5 A. This is intensified at the equa- 

 tor and is therefore produced by a periodicity in the plane of the thylakoid 

 membrane. 



Fig. 6 shows scattering curves of a preparation photographed with a small 

 angle camera according to Kratky (Fig. 7). The little tubes are oriented 



Fig. 6. Scattering curves of layers of oriented chloroplasts 

 dried on glass plates. 



a Scattering in the meridian O-O-O 



b Scattering in the equator O O- • • • O 



c Scattering caused by the stacking of thylakoids 



Fig. 7. Kratky-camera with quadratic cross section of the X-ray 



