92 THE GERM THEORY OF DISEASE. 



is the same provision precisely. Surrounding the embryo, 

 there is laid up a store of formed material for the nourish- 

 ment of the young plant until such a time as it shall have de- 

 veloped its roots and leaves, the organs by which it gathers its 

 food, sufficiently for this purpose. 



In neither of these is the food material in a condition to be 

 formed into the tissues of the young animator plant, without 

 remoleculization. It must be redigested before it can be 

 assimilated by the embryo. This process has been best 

 studied in the seed. Here it is found that the embryo elimi- 

 nates a true digestive substance, called diastase, the office of 

 which is the digestion of the store of food material. Of this 

 substance Regnault says : " A peculiar nitrogenous substance, 

 called i diastase/ which possesses the property of converting a 

 large proportion of fecula (starch) into dextrin, and even into 

 sugar, when its action is sufficiently prolonged, exists in the 

 germ of the cerealia and in tubercular vegetables. It appears 

 to be formed at the moment of germination, probably at the 

 expense of the albuminous matter contained in the grain, as 

 it resides in the very origin of the germ, and in the eye of the 

 tuber; and its use in the vegetable economy appears to be 

 that of disaggregating the amylaceous matter, and transform- 

 ing it into an isomeric soluble substance, which the vital 

 forces then change into other isomeric, but insoluble sub- 

 stances, such as cellulose, which is to form the framework of 

 the growing plant." 



This substance is very well known, and its action on the 

 starch has been closely studied. It may be precipitated by 

 alcohol, and obtained in the form of a powder, and preserved 

 fora long time, and when redissolved in water will still pro- 

 duce its effect on starch. This effect, like that of other sol- 

 uble ferments, is not to be explained by the ordinary chemical 

 laws. One part of diastase will convert 2000 parts of starch 



