1916 Karrerj on Nereocystis 229 



Chlorine. — The sections were placed in a solution of silver ni- 

 trate and the white flocculent precipitate of silver chloride was formed. 

 This was recrystallized by adding several drops of concentrated am- 

 monium hydroxide and allowing to evaporate. Definite crystals of 

 silver chloride were obtained. 



Sulphates. — Barium chloride was used to precipitate the sulphates, 

 since it forms an insoluble precipitate with silicates and sulphates only. 

 Silicates are lacking in Nereocystis and thus a precipitate would indicate 

 only sulphates. These results were checked by testing the solubility of 

 the precipitate in acids, barium sulphate being insoluble in dilute hydro- 

 chloric and nitric acids. 



Carbonates. — Sections were mounted on a slide, under a cover glass, 

 in a concentrated solution of hydrochloric acid. Bubbles could easily be 

 seen under the microscope. The carbonates were decomposed b}^ the acids 

 and bubbles of carbon dioxide were given off. 



Phosphates. — The sections were placed in a solution of dilute am- 

 monium molybdate and heated for a half hour at 50° C. A yellow amor- 

 phous precipitate of (NH4).,P04.Mo03 was formed. 



Iodine. — A 10% solution of sodium nitrite was added to sections on 

 a slide, together with a few starch grains. After a few minutes a few 

 drops of a 5% solution of hydrochloric acid were added. Bubbles of 

 hydrogen iodide were immediately formed. If now a cover glass is put 

 over the sections so as to keep the bubbles from escaping, the starch grains 

 next to the bubbles are colored blue. This was found to give better results 

 than the method suggested by Molisch and Tunmann. 



Table 1. Summarising the results obtained in the preceding experiments. 



Fronds— Ca Mg- Na K CI So^ CO3 PO4 I 



Total reaction 2 1 3 3 3 2 2 1 2 



Reaction in cell 2 1 1 1 3 2 1 1 



Stipe — 



Total reaction 2 1 3 3 3 2 2 1 2 



Reaction in cell 2 1 1 1 3 2 1 1 



Holdfast — 



Total reaction 2 1 3 3.3 2 2 1 2 



Reaction in cell 2 1 1 1 3 2 1 1 



The fig-ures 1, 2, 3 denote little, medium, and great intensity of the reaction, 

 respectively. 



The above data indicate the success of microchemical technique, not 

 the demonstration of additional compounds in the kelp, since these con- 

 stituents have been found to be present by macrochemical analyses. How- 

 ever, this method has shown that all these constituents occur in solution in 

 the cells of the fronds, stipe and holdfast of the plant. 



The permeability of the cell to the reagent undoubtedly is a factor 

 in the success of microchemical analyses. If the protoplast is imperme- 

 able to it. no reaction could occur. But if the presence of the solution 



