14 CHEMISTRY OF PLANTS. 



It will now be easily apparent from what has been said, that without 

 a simultaneous application of the microscope and chemical re-agents it is 

 utterly impossible to think of a true and fundamental knowledge of starch. 

 Starch is gradually dissolved in the full-grown potato, so that after three 

 months there is scarcely a trace of it to be met with in that vegetable, even 

 where it is in a perfectly sound condition. This solution is most essen- 

 tially different from all others that we are able to bring about. The 

 individual granule retains to the last moment its solidity, and is only gra- 

 dually attacked from the exterior towards the interior ; the extremities of 

 the longitudinal sections offering the greatest resistance, on which account 

 the granule after a time resembles a knotty twig, owing to the promi- 

 nent appearance of the rest of the layers. The same thing occurs in the 

 germination of the cereals, and in the solution of starch which takes place 

 through diastase, but only at a temperature of 70 C.,* which corresponds 

 entirely in form with the solution by sulphuric acid, and has been referred 

 by chemists, with an inconceivable degree of superficial carelessness, to 

 the process in living plants. 



B. On the Occurrence of Starch in various Forms in the 

 Vegetable Kingdom. 



We have only one treatise, and that by Fritsche (Poggend. Ann. 

 vol. xxxii.), deserving of notice, on the differences of starch in different 

 plants ; and this, with some few inconsiderable additions, has been 

 made use of by Meyen in his Vegetable Physiology. For the rest, this 

 work appears to have met with very little attention ; for when we read a 

 passage to the following effect in one of the most recent works, " Starch 

 appears in the form of small spherical corpuscles," (Endlicher und 

 linger, Grundziige derBotanik,) we may easily see that the authors have 

 neither made original observations on the subject, nor even read anything 

 regarding it. The forms of starch are exceedingly various, and often, 

 as Fritsche remarked, so characteristic, that we may easily, by means of 

 the starch, determine the plant, at any rate with reference to its genus 

 and family. I subjoin the following tabular list of the forms with which 

 I am acquainted. 



I. AMORPHOUS STARCH. 



Hitherto I have found amorphous starch only in two phanerogamic 

 plants, it occurring then paste-like in the cells, as in the seeds of Car- 

 damomum mimis, and in the bark of the Jamaica Sarsaparilla. In the 

 case of the latter, however, it is not improbable that the method of dry- 

 ing by the fire, common in the preparation of Sarsaparilla, may change 

 the character of the starch. The paste is most frequently found in ab- 

 normally red roots, and more seldom in the yellow ; neither of which, 

 however, have hitherto been esteemed in commerce as varieties of the 

 Jamaica Sarsaparilla. 



II. SIMPLE GRANULES. 



The majority of plants exhibit perfectly simple individual granules, 

 among which doublets and triplets only occur as exceptions. We may 

 further distinguish the following groups : 



* A temperature that would kill every vegetable embryo. 



