. Electron microscopy; proceedings of the Stockholm Conference, September, 1956 . ^Jii 3 4v- • i-:r> Fig. 1. Section througii a cell wail of date endosperm in its natural state. Magnification 5000. Fig. 2. Section through a swollen cell wall of date endosperm. Note the microfibrils between the swollen layers. Magnification 20,000. Fig. 3. Date endosperm after Turmix and ultrasonic treatment before extraction of mannan A. Magnification 25,000. Fig. 4. Date endosperm after Turmix and ultrasonic treatment after extraction of mannan A. Magnification 25,000. endosperm of palm seeds there is a
. Electron microscopy; proceedings of the Stockholm Conference, September, 1956 . ^Jii 3 4v- • i-:r> Fig. 1. Section througii a cell wail of date endosperm in its natural state. Magnification 5000. Fig. 2. Section through a swollen cell wall of date endosperm. Note the microfibrils between the swollen layers. Magnification 20,000. Fig. 3. Date endosperm after Turmix and ultrasonic treatment before extraction of mannan A. Magnification 25,000. Fig. 4. Date endosperm after Turmix and ultrasonic treatment after extraction of mannan A. Magnification 25,000. endosperm of palm seeds there is available a material which contains mannan, one of the most important hemicelluloses. in a more or less pure form. An attempt has therefore been made to gain some knowledge of the submicroscopic structure of man- nans by studying the endosperm of date seeds {Phoenix dactylifera L.) and ivory nuts (Phytelephas macrocarpa Ruiz et Pav.). Ludtke (4) has shown that there are two different mannans in the cell walls of ivory nut, mannans A and B which differ from each other by their solubility in dilute alkali. The chemical structure of the two mannans has been studied by Klages (2, 3) and recently by Aspinall, Hirst and coworkers (I). According to them these mannans are both com- posed of two types of molecules, one having a mannopyranose residue as non-reducing end group, the other a galactopyranose residue. The two man- nans should, according to Aspinall, differ from each other only in their molecular size. By determination of the end groups Aspinall has calculated a degree of polymerization of 10-13 for mannan A and of 39^0 for mannan B. It might however seem doubtful that the difference between the two mannans should lie in their molecular size only. In that case it would be very difficult to understand why there should not exist between the mannans A and B a series of molecules with a degree of polymerization between 10 and 40. Moreover, this small difference in chain leng
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