DETECTION OF SUBERIN, ETC. 143 



fresh solution of chlorophyll must be used, and the treatment 

 should last for at least fifteen minutes in the dark. The 

 sections may be washed in and examined in water. (Lig- 

 nified walls are unacted upon by this and the following 

 reagents.) 



6. Similarly the same membranes are stained red by treat- 

 ment with alcoholic solutions of Alkannin, Sudan III and 

 Scharlach R. 



7. If a section of the material be treated first with eau de 

 Javelle, in order to destroy any tannins which may be present, 

 suberized walls are stained very deeply with a solution of 

 cyanin in 50 per cent alcohol to which an equal volume of 

 glycerin has been added. Lignified walls will not be stained 

 owing to the preliminary treatment with the eau de Javelle. 



8. Corky walls are stained orange-yellow by an alcoholic 

 solution of extractum orleancB spirit which must be filtered 

 before using. 



FURTHER REFERENCES. 



Cross and Bevan : " Researches on Cellulose," London, 1895, 1901, 1906, 

 1912. 



Cross, Bevan, and Sindall : "Woodpulp and its Uses," London, 1911. 

 Worden: "Nitrocellulose Industry," London, 1911. 

 Schwalbe : " Die Chemie der Cellulose," Berlin, 1912. 



THE SYNTHESIS OF CARBOHYDRATES IN 

 GREEN PLANTS. 



INTRODUCTORY— ALDEHYDES. 



In view of the important part played by aldehydes in ques- 

 tions relating to photosynthesis it appears desirable to draw 

 attention to the chief properties of these substances before 

 passing on to a consideration of the synthesis of carbohydrates 

 in green plants. 



It is, of course, well known that the aldehydes are the first 

 products of the oxidation of primary alcohols : — 



CH3OH + O = HCHO + HjO 

 Methyl alcohol Formaldehyde 



CH.,CHaOH + O = CH3CHO + H2O 

 Ethyl alcohol Acetic aldehyde 



