AMMONIUM SALTS UPON PLANTS. 267 



1. Ammonium carbonate. 



2. Ammonium sulphate, 



3. Ammonium chloride. 



4. Sodium carbonate.\ 



5. Sodium sulphate \ for control. 



6. Water. j 



Experiment t^'ith Barley. 



Time of exposure to darkness : seven days ; Temperature of 

 greenhouse : minimum 10°, inaximum 19° C. 



Two j'oung plants 24 — 28 cm. high were placed in each 

 vessel (March 3). 



The noxious action upon the two starving plants (A), of am- 

 monium carbonate in a dilution of o.\% was very evident, when 

 the plants were compared with the well nourished two control 

 plants (B) in the same solution. The latter had not only numer- 

 ous young rootlets but also five still healthy leaves which were 

 only a little yellowish at their base, while there was not a single 

 healthy leaf noticed in the other case ; a yellowish colouration was 

 seen all along the stems, and the leaves were more or less dried 

 up from the tip downward. 



The other control plants (A) kept in o.\% sodium carbonate 

 were still alive, although they had more or less yellowish leaves, 

 while those in 0.^% sodium carbonate were much injured. How- 

 ever, tliere was a great differeiKe noticed in the plants (B) j^laced 

 in sodium carbonate compared with those kept in ammonium 

 carbonate, both in 0.5^ solutions, the former carbonate being 

 by far less noxious than the latter, proving that it is not tlie 

 alkaline reaction itself which exerts the noxious action. 



Some etiolation was however noticed more or less in all the 

 plants, and also the withering of some leaf-tips even with most 

 of the plants (B), although this phenomenon was much more 

 noticeable with the plants (A). 



The following table shows the results of some of the observa- 

 tions : — 



