STRUCTURE.] FLUID STARCH IODINE, 125 



geneous mass. Now if such minute cells were to acquire 

 the chemical condition of starch and its physical properties, 

 they would be placed quite in the same manner as the grains 

 of that substance lie in the interior of Maize, and could not 

 be distinguished. Upon this supposition the theory of starch 

 would be that, 1, vegetable mucus is secreted in the interior 

 of the cell; that, 2, cytoblasts are generated in that mucus; 

 and that, 3, the cytoblasts, under the influence of the plastic 

 power of vitality do not become common cells, but change 

 their physical and chemical nature till they are finally 

 resolved into starch grains. 



The mucus of vegetation does in fact sometimes take on 

 the chemical quality of starch without becoming organised. 

 In other words, fluid (not granular) starch is known to occur 

 in some plants, as has been proved by Link, who remarked it 

 in the tubercles of Salep and of the common Orchis latifolia, 

 both before and after flowering, as he has shown in fig. 13 of 

 the 16th plate of his admirable Anatomical figures. 



He therefore concludes that the unformed matter of starch 

 is capable of transforming itself into grains. " A thick fluid 

 mass," he adds, "which cannot be coloured by iodine, mixed 

 with large granules of starch, is also found in the seed of 

 Phaseolus vulgaris. Large and small granules of starch are 

 generally mixed with each other. The most external cells of 

 the grain of wheat, in which, according to Payen, the most 

 gelatine is contained, contain small granules of starch, as if 

 they were developed from gelatine." " The mucilage of Marsh 

 Mallows also, at least partially, belongs to the genus Starch ; 

 it forms grains, which become blue on the application of 

 iodine, which dissolve in cold water, and which form a mucus 

 that is likewise turned blue by the tincture of iodine." (See 

 Icon. Anat. Bot., table 16, fig. 14, a. b.) 



The exact nature of the action upon starch of iodine, by 

 which that substance has been found in all cases discoverable, 

 has been investigated by Mohl with his usual consummate 

 skill. It has been supposed, that starch is the only known 

 substance which becomes blue or violet when acted upon by 

 iodine. Mohl has, however, shown either that other sub- 

 stances are so acted upon, or that starch exists in other states 



