158 Mr. E. H. Acton. The Assimilation of Carbon 



~No. 1. — -Experiments with Acrolein. 



The acrolein was prepared by the usual method,* viz., distillation 

 of glycerin and acid potassium sulphate, the distillate being in the 

 first instance collected in a receiver over PbO and CaCl 2 to remove 

 acrylic acid and water. The product was three times " rectified " 

 over CaCl 2 , and preserved in a sealed tube over a few fragments of 

 CaCl 2 till required for use. 



The " acrolein-ammonia " was prepared by Claus's method, f viz., 

 acrolein vapour was passed into strong aqueous ammonia, the excess 

 of ammonia driven off by warming, and the reddish solid acrolein- 

 ammonia precipitated by addition of excess of ether alcohol. 



The solid was dissolved in water immediately before use. 



Acrolein-ammonia is a condensation product having the formula 

 C 6 H 9 NO. (2C 3 H 4 0+NH 3 == C 6 H 9 NO+H 2 0.) 



The crystals of acid sodium sulphite compound, of which the 

 crystals are somewhat insoluble, can be easily prepared in the ordinary 

 way for these compounds. Composition, 2NaHS0 3 "C 3 H 4 0. 



Owing to the fact that acrolein is very liable to undergo spon- 

 taneous decomposition on standing in contact with water, and the 

 extremely offensive nature of the substance in a free state, I employed 

 certain soluble acrolein compounds, as well as the uncombined alde- 

 hyde ; but, although these compounds did not act so prejudicially on 

 the plants, they caused them to assume an unhealthy appearance after 

 4 — 5 days, and two out of six plants which had been grown in the 

 solutions under the conditions described on p. 160 failed to recover 

 when again planted under normal circumstances, although fully 

 supplied with water and shaded from intense direct sunlight. 



Details of these experiments are given on the following pages. 

 I think they prove conclusively that plants are unable to form starch 

 in their leaves from acrolein or its compounds when supplied to them 

 as such, and that it is therefore doubtful whether the synthesis of 

 glucose by Fischer and Tafel from acrolein has any direct bearing on 

 the formation of starch in plants. The results with ordinary alde- 

 hyde (acetalclehyde) and some of its compounds were also negative 

 (see pp. 163 — 164), although these did not seem to have any injurious 

 effect on the plants. In 1 per cent, solution no formation of starch 

 could be detected, whether the substance was supplied to the roots, 

 cut branches, or the external surface of the leaves. 



No. 1. — Experiments with Acrolein. 

 I. With free aldehyde — 



* See F. Beilstein, ' Handbucli der organischen Chemie,' 2nd Edit., p. 360. 

 f ' Liebig's Annrlen,' vol. 130, 1864, p. 185. 



