THE ORGANIC ELEMENTS. 19 



sequently discovered the property possessed by starch of being coloured 

 blue by iodine. 



Few substances have been so comprehensively treated of as starch, 

 and few have been more imperfectly and unsatisfactorily known, this 

 arising solely in consequence of neglect or superficiality in microscopic 

 investigations. A very clear and comprehensive report of PoggendorfF 

 upon the numerous works, up to 1836, written on this substance, may be 

 found in Pogg. Annal. der Chem. und Pharm., vol. xxxvii, p. 114., &c. 

 The result of the whole is concisely summed up in these striking intro- 

 ductory words : 



" No substance has been more investigated, and is yet less known, 

 than starch. It affords a striking proof of the diffuse manner in which 

 a subject may be treated if it fall into improper hands. After ten years' 

 investigations, in which the most various views have been set up on the 

 nature of starch, and when all its characteristics as a proximate vegetable 

 substance have been discussed, we are little or nothing in advance of 

 the old point of view ; and although, perhaps, we may not be wholly 

 without some extension to our knowledge in secondary points, we are 

 still entirely without fundamental grounds in proof of our having arrived 

 at the truth." 



Since Poggendorff wrote these words, eight years have elapsed. In- 

 numerable works upon starch have been published by chemists and 

 vegetable physiologists ; and, on testing more exactly what has been 

 done in Endlicher's and Unger's Rudiments of Botany, we find that the 

 labours of the last eighteen years are lost, even as far as relates to the 

 more general knowledge of this substance, whilst the whole confusion in 

 the literature of those eighteen years may be found reflected in the few 

 lines of those writers, who evidently were not able by their own ele- 

 mentary investigations to avail themselves with discrimination and 

 judgment of the extensive literature opened to them. The diametrically 

 opposite views of Fritsche and Raspail are so blended together in the 

 most extraordinary manner, that the confusion is beyond all description. 



There are two views upon the structure of starch granules decidedly 

 opposed to each other, on the assumption or rejection of which the 

 chemical judgment passed upon this substance must essentially depend. 

 The first, originating with Leeuwenhoek, and subsequently further de- 

 veloped by Raspail, tends to prove that the individual starch granules 

 consist of a tough sac, and semi- liquid, easily soluble contents (Dextrin), 

 and that both parts are chemically different. This view effected the 

 refutation of the diffuse works of the French chemists, who, although 

 they differed upon words and secondary points, yet agreed in the main 

 that starch was no proximate vegetable matter, and that the starch 

 granule was composed of substances differing considerably in a chemical 

 point of view. Among these may be reckoned especially the works of 

 Guibourt, those earliest written by Payen and Persoz, and those of 

 Guerin-Varry. Finally, after giving many proofs of their incapacity 

 to compose an unprejudiced and thorough analysis of organic substances, 

 Payen and Persoz came to the conclusion, " that starch purified from 

 all extraneous matter was a simple, homogenous, proximate vegetable 

 substance." Raspail's view was entirely given up, and the structural 

 relations of starch not more thoroughly pursued. Such was the state of 

 things in France. In Germany, starch was first more accurately 

 examined by Fritsche*, and by aid of the microscope, which is indis- 



* PoggendorfTs Ann. vol. xxxii. p. 129. (1834). 

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