190 LECTURE IX. 



down and building up of albumin in the animal organism. By means of 

 such a progressive decomposition the cell is able to transform and build 

 up anew the albuminous material that reaches it, so that it is suited for all 

 the requirements of the cell-content. It is not difficult to understand how 

 from a definite compound-albumin all sorts of different proteins may be 

 prepared containing the various amino acids in proportions quite different 

 from those in the original mother substance. It is not necessary that 

 such a transformation should involve a complete reduction of the original 

 protein to its fundamental constituents; a partial decomposition may 

 answer all requirements. Although the details of fermentation are 

 not yet definitely known, we can, however, consider the fundamentals of 

 protein decomposition as fairly well established. We can also point out 

 the very close analogy to the disintegration of the polysaccharides. We 

 know that starch, before it is converted into dextrose, undergoes many 

 intermediate transformations, concerning the exact nature of which we are, 

 up to the present time, as much in darkness as we are in regard to the albu- 

 moses and peptones. We are only able to recognize the former as mixtures, 

 calling them dextrins. The first definite chemical cleavage-product is the 

 disaccharide maltose. The dextrins, which we still consider as com- 

 plicated polysaccharides, correspond to the peptones. The dextrins and 

 related compounds may very easily be considered as mixtures of long 

 chains of dextrose molecules. The maltose would then correspond to a 

 dipeptide. The conditions in the carbohydrates are comparatively simple, 

 because starch is considered as composed of a series of only one kind of 

 molecular combination, i.e., dextrose, whereas, with the albumins, there 

 are many different fundamental substances. On the other hand, we are 

 also acquainted with proteins like the protamine, salmin which are of 

 simple construction, being mainly composed of arginine, while we also know 

 of polysaccharides in the vegetable world which are not far behind the 

 proteins as regards complexity. As an example of a " mixed " disaccharide, 

 we have cane-sugar, which breaks down into one molecule of dextrose and 

 one of laevulose, and also to mannorhamnose, which splits into one 

 molecule of mannose and one of rhamnose. 



We are also acquainted with mixed trisaccharides. On hydrolyzing 

 rhamninose, a glucoside occurring in the fruit of Rhamnus infectoria, two 

 molecules of rhamnose and one of d-glucose are obtained. Gentianose, 

 from varieties of Gentiana, contains two molecules of glucose and 

 one molecule of fructose. We know of a large number of poly- 

 saccharides, in whose constitution many sugar varieties participate: pen- 

 toses, methylpentoses, hexoses, etc. We only mention these examples 

 to illustrate the analogy between the polysaccharides and the proteins. 

 A very large number of combinations are possible by using many different 

 constituents. The ^proteins predominate in the animal organism. They 



