ZOOLOGY AND BOTANY, MIOROSCOPYj ETC. 751 



Cellulose. — Cellulose, as it is most frequently present in the cells, 

 that is in the condition of polymerization not exceeding (CeHjoOs)^, is 

 soluble in Schweizer's ammonio-cupric solution. More condensed 

 (for instance elder pith, the walls of thickened fibres, old vessels, 

 ligneous cells) it is insoluble in the same reagent. 



Schweizer's solution alters with time, therefore it ought to be used 

 freshly prepared. It is obtained by pouring ammonia on copper- 

 turnings, in a funnel ; the liquid is again poured over the copper until 

 it is coloured deep blue. 



As the solution of cellulose can only be effected by a large 

 quantity of nitrite of ammonia, care must be taken to keep a constant 

 current of the liquid passing between the two glasses between which 

 the preparation is compressed. For this purpose pieces of filtering- 

 paper are used, which absorb the liquid at the edge of the cover-glass, 

 whilst some drops of the solvent are placed at the opposite edge. The 

 operation is hastened by disusing the cover-glass where large sections 

 are being treated. 



When the preparations are numerous and resisting they can be 

 shaken together in a little flask filled with Schweizer's liquid, and 

 subjected to several washings. This is the most rapid process. But 

 if the preparations are at all delicate the first method alone is practi- 

 cable ; the operator should follow under the Microscope the difierent 

 stages of the solution. The observation is easy with a low power ; 

 but directly it requires more than 200 diameters it becomes trouble- 

 some. In this case it is better to increase the power of the eye-piece 

 alone ; high-power objectives are inappropriate, the distance of their 

 front lens from the preparation is so small that they risk being wetted 

 by the reagent. 



The butyric fermentation offers a slower but more accurate means 

 of isolating in a preparation all the non-cellulose membrane by deter- 

 mining the cellulose. The organs or the sections from which we wish 

 to eliminate the purely cellulose portions are placed in a glass of 

 water, to which are added pieces of radish-roots, haricot-beans, or 

 broad-beans, a very small quantity of sugar and powdered carbonate of 

 lime. The mixture is shaken up and left exposed to the air. The 

 fermentation is increased by keeping the vessel in a temperature of 

 about 30^ C. 



When, carbonate of lime being in excess, there is no further dis- 

 engagement of gas, the Bacillus amylobacter has formed its spore, and 

 the fermentation has ceased ; all the cellulose has then been, by a 

 series of successive hydrations, converted into glucose, and the 

 glucose decomposed into carbonic acid and butyric acid. The role of 

 the carbonate of lime is to allow the formation of butyrate of lime as 

 butyric acid is produced ; this acid, free and accumulating in the 

 liquid, would arrest the development of the Bacillus long before the 

 destruction of all the cellulose. 



Like Schweizer's solution, the butyric ferment does not attack 

 cellulose whose condensation exceeds (CeHiQOg)^. The action of the 

 microbe is indeed so special that it is only exercised on a certain 

 kind of this compound, although no chemical reagent shows two 



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