120 ADAPTATIONS IN THE PRODUCTIONS OF DIASTASE. 



carried into the general circulation. Or when, as in the potato, much 

 more starch is present than is in many cases requisite, its function ceases 

 long before the whole of the starch disappears. Its presence is necessa- 

 ry only until the leaves and roots are fully formed — when the plant is 

 enabled to provide for itself, and becomes independent of the starch of 

 the seed. When this period arrives, therefore, the production of dias- 

 tase is no longer perceived. 



This I have said is one of the purposes which appears to be served by 

 diastase in the vegetable economy. That it is the only one we have no 

 reason to believe. There may be others quite as interesting which we 

 do not as yet understand. This is rendered more probable by the fact 

 that the diastase contained in one pound of malted barley is capable of 

 converting into sugar five pounds of starch.* (Liebig.) And though 

 at the temperature at which the seed germinates, more of this substance 

 may be necessary to transform the same weight of starch than is re- 

 quired in our hands, when aided by artificial heat, — yet as we never in 

 the ordinary course of nature find any thing superfluous or going to 

 waste, there is reason to believe that the diastase may be intended also 

 to contribute directly to the nourishment and growth of the plant. As 

 it contains nitrogen, it must be derived from the gluten or vegetable al- 

 bumen of the seed ; and as a young plant of wheat, when already many 

 inches from the ground, contains no more nitrogen than was originally 

 present in the seed itself (Boussingaull), this diastase may only be the 

 result of one of those transformations of which glutenf is susceptible, 

 and by which it is rendered soluble, and capable of aiding in the pro- 

 duction of those parts of the substance of the growing plant into which 

 nitrogen enters as a necessary constituent. 



It may not be uninstructive if we pause here for a moment and con- 

 sider the beauty of the arrangements we have just been describing. In 

 passing through a new and interesting country we do not hesitate, at 

 times, to stop and gaze, and leisurely admire. We cannot otherwise 

 fully realize and appreciate its beauty. So in the domains of science, 

 we cannot be ever hurrying on — we must linger occasionally, not only 

 that we may more carefully observe, but that we may meditate and 

 feel. 



You see how bountifully nature has provided in the seed for the nour- 

 ishment of the young plant, how carefully the food is stored up for i;, 

 and in how imperishable a form — how safely covered also and protected 

 from causes of decay ! For hundreds of years the principle of life will 

 lie dormant, and for as many the food will remain sound and undimin- 

 ished till the time of awakening comes. Though buried deep in the 

 earth, the seed defies the exertions of cold or rain, for the food it contains 

 is unaffected by cold and absolutely insoluble in water. But no sooner 



* It is the diastase in malt which dissolves the starch of the barley in the process of brew- 

 ing, but as the diastase contained in malt is sufficient to dissolve so large a quantity of starch, 

 it is obviously a waste of labour to malt the whole of the barley employed. One of malt to 

 three of barley would probably be sufficient in most cases to obtain a wort containing the 

 whole of the starch in solution. Advantage is taken of this property in the manufacture of 

 the white beer of Louvaio, and of other places ki Flanders, and in Germany, where the light 

 colour is secured by adding a large quantity of flour to a decoction of a small quantity of 

 barley. 



t That diastase is merely transformed gluten we cannot say, because the exact chemical 

 constitution of diastase is as yet unknown. 



