The Typical Cellulose and the Cellulose Group 65 



hydrogen in the other and opposite direction within the molecule : 

 a decomposition, therefore, of the electrolytic type. Nothing is 

 known of the intermediate stages of the resolution of the C G H, 2 O a 

 into 2 [C a H 5 OH + COJ ; the decomposition is rather of an ex- 

 plosive character, and we have so far no means of investigating its 

 mechanism. 



The sugars are, of course, not * organised ' as such into cellular 

 tissue, but are built up into aggregates of specialised constitution. 

 The reabsorption of such aggregates into the general circulation 

 of nutrient material of the plant, as indicated under (i), is the re- 

 sult of proximate resolution of these aggregates. It must be borne 

 in mind here that changes of this order have been brought to 

 light by physiological and histological methods ; and with very 

 little regard to the chemistry of the changes or, indeed, the actual 

 composition of the tissue substance. Later investigations are 

 differentiating these tissue-substances altogether from the celluloses 

 of the cotton type, and in reading this section the student may be 

 reminded that in the classification of the celluloses (which 

 follows later, p. 85), it will be shown that so-called 'celluloses' 

 susceptible of hydrolytic degradation are of an inferior order of 

 molecular aggregation probably rather resembling that of the 

 starch- dextrin series. 



We may note here more particularly an important paper by 

 Brown and Morris (J. Chem. Soc. 1890, 57, 458) upon the 

 * Germination of some of the Graminese.' It is generally known 

 that the cell wall of endosperm cells containing nutrient substances, to 

 be supplied to the embryo in its earliest stages of growth, are broken 

 down, as a preliminary to the appropriation of the cell contents. 

 The general mechanism of the process has been elucidated by 

 the above observers, even to the localisation of the cellulose- 

 dissolving enzyme (cyto-hydrolyst). This enzyme does not exist 

 in the resting seed but is formed in the process of germination. 

 From a cold water extract of an air-dried malt the enzyme is pre- 

 cipitated by alcohol. An extended investigation of its activity 

 showed that it rapidly disintegrates the parenchymatous tissue of 

 the potato, carrot, turnip, apple, beet, c. The elegant methods 

 of experiment pursued by the above authors are typical of chemico- 

 biological work, and should be thoroughly mastered by the 

 student. 



