igi6] RIGG—SOIL TOXINS 300 



3. The toxicity of the very dilute solutions (but not of the strong 

 solutions) was nearly destroyed by neutralization with sodium 

 hydrate. 



4. The toxicity of solutions resulting directly from the decay 

 of the rhizome is destroyed by shaking them with animal charcoal. 



5. The water extract of the fresh rhizome made under 15 lb. 

 pressure in an autoclave is toxic to growing plants. 



6. The rhizome and the products of its decay contain some 

 ether-soluble toxic material. 



7. Some of the toxic material in the products of the decay of 

 these rhizomes is volatile at 40 C. 



8. The toxicity of even concentrated solutions resulting directly 

 from the decay of these rhizomes can be removed by precipitation 

 with ammonium sulphate. 



9. The water extract of the ash from these rhizomes is basic 

 and toxic. 



10. The products of the decay of potatoes, of turnips, and of the 

 rhizomes of Castalia odorata and Typha lalifolia are also toxic to 

 Tradescantia, but slightly less so than those of Nymphaca. 



University of Washington 

 Seattle, Wash. 



LITERATURE CITED 



1. Archichowsky, V., Die Wirkung der Giftstaffe verschiedener Konzen- 

 trationen auf die Sammen. Biochem. Zeit. 50:233-244. 1013. 



2. Baumax, A., and Gully, E., fiber die freien Humussauren des Hochmoors. 

 Mitt. K. Bayr. Moorkulturanst. 4:31-56. 1910; see also Science N.S. 

 40:492. 1014. 



3. Bottomly, W. B., The significance of certain food substances for plant 

 growth. Ann. Botany 28:531-540. 1914. 



4. Brown, A. J., The selective permeability of the covering of the seeds of 

 Hordeum vulgare. Proc. Roy. Soc. 818:82-93. 1909. 



5. Czapek, F., rJber eine Mcthode zur direkten bestimmung der Oberblachen- 

 spannung der Plasmahaut, von Pflanzenzellen. Jena. 191 1. 



6. Dachnowski, A., Bog toxins and their effect upon soils. Box. (jaz. 

 47:389-405. 1909. 



7. — — , Physiological properties of bog water. Box. Gaz. 39:348-355. 1905. 



8. Dandeno, L. B., Mutual interaction of plant roots. Report Mich. Acad. 

 Sci. 11:24-25. 1909. 



9. Exper. Sta. Record 15:780. 1903-1904. 



