1. There is a large amount of nitrate in the organs of A. retroflexus. The stem and branches are the primary nitrate storage organs. The rate of nitrate absorption increases with the aging of the plant, perhaps partly being due to the development of the root system with numerous branching rootlets, increasing the radius of the feeding area from a few inches to 2 ft. or more. 2. This high capacity for nitrate absorption and storage must be an important factor in making Amaranthus a very successful competitor against cultivated plants, so effectively withdrawing as it does the nutrient element most commonly limiting plant production. It would be interesting to know how generally and to what degree weeds possess this power. 3. The carbohydrates and nitrogen compounds fluctuate throughout the growing period. The fluctuation of the carbohydrates is in the reverse order of the nitrogen compounds. This inverse ratio is not a truly mathematical constant, but in general when the carbohydrates are high the nitrogen...