ritter: astragalus mollissimus. 201 



A laboratory investigation by Alsberg and Black ('12) on the 

 barium question shows that barium is not responsible for the 

 toxicity of loco weeds. Their evidence is : Many plants which are 

 harmless contain as much or more barium than loco weeds; there 

 are enough other metals present to explain the action attributed 

 to barium; extracts of alfalfa, which are prepared similarly to 

 extracts of loco weed which are toxic to laboratory animals, are 

 foimd to be toxic to some laboratory animals; the barium is 

 present in "at most but minute traces." 



ORIGINAL investigation. 



Alkaloid. The alkaloid test is a reddish-brown precipitate 

 with bromine or iodine. When the bromine reagent is applied to 

 sections of the petiole, leaflet or stem, and a control (soaked in 

 alcoholic tartaric acid for two days, then in water one day), no 

 difference can be seen in the sections. The same is true when 

 potassium iodide-iodine is used as an indicator. Both of these 

 tests were repeated many times on all parts of the freshly picked 

 plant, indicating no alkaloids. 



As a control to the test for alkaloids, sections of nux vomica 

 seeds, calabar beans and belladonna root were soaked in the sol- 

 vent for alkaloids. These and fresh sections were tested for alka- 

 loids at the same time with potassium iodide-iodine. A very 

 noticeable difference was discernible. The fresh sections show a 

 deep orange-brown color; the alkaloid-free sections a light yellow 

 color, if any. So if an alkaloid were present in my loco weed, a 

 difference in color between fresh and control sections should have 

 been detected; but as there was none, the conclusion reached is 

 that there is no alkaloid present. 



Sugar. Sugar is present in a fairly large amount. When sec- 

 tions of the leaf or stem are boiled in Fehling's solution, at first 

 there is no change, but after boiling longer the brick-red precipitate 

 appears, indicating that cane sugar or a glucoside is probably 

 present. This is indicated in all the cells except the bast fibers 

 and water tubes. Loco weed gathered at 9 :30 at night showed the 

 presence of a quantity of sugar in the green parts on boiling with 

 Fehling's solution; that gathered early in the morning not so 

 much. 



Starch. Starch is present in great quantities in the stem, in 

 the pith, medullary rays, pericycle and cortex. In the petiole the 

 starch sheath contains it abundantly, but there is little in the pith. 



