30 PRACTICAL BOTANY. 



the reactions mentioned above ; the tissues of Fungi require a long 

 treatment (three or four weeks) with potash. It appears that in 

 these cases other substances are present which must be extracted 

 from the cell- walls before the characteristic cellulose-reaction can 

 be obtained. 



iv. Dissolved by ammoniacal solution of cupric hydrate 

 and by strong sulphuric acid. 



v. Stained by solutions of carmine and of hsematoxylin 

 which contain a mordant, by methylene blue, and in 

 various degrees by other aniline colours. 



1. Lignified cell-walls 



i. Coloured yellow by iodine and Schulze's solution, 

 ii. Coloured deep brown by iodine and sulphuric acid. 



iii. Coloured bright yellow when treated with solution 

 of aniline chloride or sulphate, the colour being intensi- 

 fied by subsequent treatment with hydrochloric or 

 sulphuric acid. 



iv. Coloured red when treated with solution of 

 phloroglucin (p. 21), and with strong hydrochloric acid. 



v. Coloured green when exposed to light (\ 1 min.), 

 after treatment with carbolic and hydrochloric acids 

 (p. 22). 



vi. Swollen and slowly dissolved in strong sulphuric 

 acid ; dissolved slowly in concentrated chromic acid ; 

 soluble in Schulze's macerating fluid (p. 23). 



When the lignification is not complete the cell-wall becomes 

 disorganised and dissolves partially in strong sulphuric acid ; this 

 is due to the presence of a considerable proportion of cellulose. 

 Lignified cell- walls give the characteristic cellulose-reactions after 

 maceration in Schulze's fluid. The solubility of lignin in this 

 fluid affords a means of isolating the cells of a woody tissue. 



vii. Stained slightly or not at all by solutions of 

 carmine and hsematoxylin, but readily by aniline colours 



