THE ANNALS 



AND 



MAGAZINE OF NATURAL HISTORY. 



[THIRD SERIES.] 

 No. 22. OCTOBER 1859. 



XXV. — On the supposed Existence of Cellulose in Starch-grains. 

 By H. VON MoHL *. 



On no vegetable structure has so great a number of micro- 

 chemical researches been instituted as upon starch-grains ; and 

 of none have the structure and chemical composition, in the 

 course of time, been so contradictorily explained. The view of 

 Baspail, that the starch-grain consisted of a vesicular envelope 

 insoluble in water, with soluble gummy contents, was overturned 

 by the researches of Fritzsche and of Payen, who appeared to 

 have demonstrated beyond all doubt that the starch- grain con- 

 sisted of superimposed layers, formed of one and the same che- 

 mical compound throughout the whole thickness of the grain ; 

 but Nageli believed, in his earlier researches at least, that he 

 could discern an outer cellulose membrane, — which opinion was 

 again questioned by myself. Muschke (Journ. f. Prakt. Chemie, 

 Ivi. p. 400) still more strongly asserted the presence of cellulose 

 in the starch-grain, thinking he had found the latter to consist 

 of a number of concentric membranes formed of cellulose, be- 

 tween which the starch -substance was deposited, and this in a 

 double modification — one soluble in water, which formed the 

 bright layers of the starch-grain, and one insoluble, of which 

 the dark layers were composed. All these accounts, however, 

 may now be regarded as out of date, since the recent researches 

 of Nageli ('Die Starkekorner,' Monographic, 1858) prove 

 indubitably that the whole starch-granule, in all its parts, is 

 composed of two distinct chemical compounds, which in his 

 view form a kind of diffusion f. He arrived at this conclusion 



* Bot. Zeitung, July 1st & 8tli, 1859; translated by A. Henfrey, F.R.S. 



t A very long account of tlie structure and development of starch has 

 just been published by Trecul in the * Ann. des Sc. nat.' ser. 4. t. x. It does 

 not contain any new matter of great importance : he advocates the view 



Ann. ^ Mag. N. Hist, Ser. 3. Fo/.iv. 16 



