The Typical Cellulose and the Cellulose Group 75 



of the living cell ; but, although, therefore, nitrogen must be 

 regarded as essential to the process, the plant builds up non- 

 nitrogenous materials, both immediate and ultimate. (3) That the 

 source of energy which determines these constructive changes is 

 that of the sun's rays ; that portion of the solar radiation chiefly 

 concerned being included between the wave lengths x^jhnj 

 Ttf&zbu mm., with a maximum effect corresponding to the yellow- 

 green of the spectrum. 



Generally, jt may be fairly assumed that the CO 2 of the atmo- 

 sphere is 'loosely 3 synthesised with protoplasmic products or chlo- 

 rophyll, 1 and so brought within the range of the specific molecular 

 activities, representing what we know in the aggregate as vitality. 



Constitution of Cellulose. From the preceding general 

 account of the properties and reactions of the typical cotton 

 cellulose we might be expected to be able to deduce its consti- 

 tutional formula. We have, however, already pointed out that 

 no purely chemical synthesis of any compound similar to 

 cellulose has been attempted ; we are, therefore, without the 

 essential criterion of the correctness of any general formula 

 which might be proposed, if only as a condensed expression of 

 the relationship and functions of its constituent groups. 



But although no such formula can be proposed having any 

 but a speculative and a tentative value, it will be a useful guide 

 to future investigation to sum up those reactions which throw a 

 direct light upon the function of the molecule as a whole, and 

 of its constituent groups. 



(1) The resolution by sulphuric acid, and subsequent hydro- 

 lysis of the esters formed in the reaction, into simple carbo- 

 hydrate viz. dextrose molecules. Cellulose is, therefore, in this 

 sense an anhydro-aggregate of the aldose groups C 6 H 12 O 6 . 



(2) Partial resolution under the action of hydrochloric acid, 

 attended by the setting free of CO groups. 



In cellulose the carbonyl groups are ' suppressed ' ; that is, 



1 This view is specifically formulated by E. Fischer, Berl. Ber. 1894., 

 3231. (Dec. 10). 



