540 



Wilhelm Menke 



model by slight, plausible alternations. This basic model, on which the scat- 

 tering curves are based, has the following properties: it consists of mem- 



5> ?.o *J V 50 



Fig. 4. Small angle scattering curves of isolated chloroplasts 

 (Antirrhinum majus), above, and living cells (Chlorella pyrenoid- 

 osa), below. 



experimental curve 



calculated curve 



difference between experimental and 



calculated (mean values) 



branes, each of which is composed of two layers of different electron density. 

 These asymmetric membranes are oriented pairwise enantionnerically toward 

 each other. One layer is continuous, the other of corpuscular structure. 

 According to the former results the corpuscular layer is protein, and the 

 continuous layer is lipid material. The dimensions of the model and the per- 

 iod of stacking can be gathered from Fig. 5. The differences between the 



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DOOOOOOOOOOOC '■ 

 300000000000C „., 



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DOCXX)000(X)OOC "" 



',:.,! , 



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 Fig. 5. Schematic transversal section through a thylakoid stack 



individual experimental scattering curves are explained by a certain variabil- 

 ity in the period and by statistical fluctuations in distance. A further point to 

 be taken into consideration in isolated chloroplasts of Antirrhinum is the 

 scattering of the regions of the lamellar system situated between the grana, 

 and in Chlorella the scattering of the matrix and of the remaining cell struc- 

 tures. The constant component is in every case the scattering of the pairs of 



