Botany in the Experiment Station. 8i 



Investigations in the Federal Division. 



PHYSIOLOGICAL INVESTIGATIONS. 



Investigations in the Federal Division have been carried on by 

 myself and were begun in the autumn of 1892. 



The three chief subjects of a physiological nature which have been 

 investigated may be referred to first. One of these the " Oedema of 

 Tomatoes " or " Dropsy " of Tomatoes, was published as Bulletin 

 No. 53, May, 1893. This trouble was characterized by numerous 

 intumescences upon the succulent stems and the veins on the under- 

 side of the leaves. The cells of the tissue in these regions became 

 greatly enlarged, the walls thin, and finally the endosmotic pressure 

 became so great that the cells collapsed. Experiments demonstrated 

 that the trouble was due to excessive root absorption while the con- 

 ditions of the greenhouse were such as to check transpiration and 

 tavor the accumulation of osmotically active substances in the tis- 

 sues. Suggestions were made as to how this trouble could be cor- 

 rected by proper lighting and ventilation of the houses. 



The second physiological trouble was a similar one on apple trees, 

 and was published in Bulletin No. 6t, December, 1893. 



The third physiological investigation was an inquiry into the food 

 value of mushrooms for higher plants and was published as Bul- 

 letin No. 240. June. 1906. The results obtained showed that a por- 

 tion of the substance of the common mushroom, and probably of all 

 Basidiomycetes, becomes available as food for autotrophic green 

 plants, just as was anticipated in the case of the decay of these 

 plants. They showed also that the common mushroom contains a 

 nearly perfect food for the higher plants, and indicate that the 

 higher plants can make use of simple ammonium compounds. Tliis 

 opens an interesting field for investigation and will perhaps aid in 

 throwing light on the symbiotic relation between fungus mycelium 

 and autotrophic green plants growing in various degrees of associ- 

 ation. 



DISEASES OF PLANTS. 

 The investigations on the diseases of plants have been carried on 

 with special reference to the determination of the cause of unknown 

 diseases, studies of the morphology of the fungi causing them and 

 especially studies of development in order to learn the life history 

 of the parasite as far as possible. In connection with this work 

 progress has been made in the improvement of devices for photo- 

 graphing of the fungi, methods of culture, etc. The chief one of 

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