EFFECTS ON PLANTS II 



phosphate, mitosis appeared in one hour.) The cells show progressively degen- 

 erative changes in three stages: (i) the cells become cloudy, due to the accumula- 

 tion of fat droplets (ascribed to lack of transformation into lecithin in the 

 absence of P); (2) the chlorophyll bands become disarranged; (3) chlorophyll 

 disappears from the chloroplasts and the cell contents become completely dis- 

 organized. Reed believed that phosphorus is more closely connected with the 

 transformation than with the origin of carbohydrates; and that in its absence 

 abnormal transformations occur. No especial susceptibility of the nucleus to 

 phosphorus deficiency has been observed, which is surprising since this element 

 is an essential component of the nucleoproteins (chromatin). 



Moore, Roaf and Knowles ('08) observed that in hyacinth and onion the 

 phosphatic ions have a peculiar effect on inflorescence. In the oat plant, Dickson 

 ('18) found the general development of the plant severely affected by deficiency 

 of phosphates. The vigor of growth is greatly decreased, the developmental 

 period shortened, and stooling prevented; the total dry weight of the plant is 

 diminished, and grain production lowered, although the weight of the individual 

 kernels and the ratio of grain to straw are increased. 



DEFICIENCY IN NITROGEN AND ORGANIC NUTRIENTS 



Nitrogen ranks with phosphorus as of primary importance, being an essen- 

 tial constituent of protoplasm in both plants and animals. Aside from those 

 cases. where atmospheric nitrogen is fixed by the aid of the nitrifying bacteria, 

 plants require nitrates or higher organic compounds of nitrogen. In spite of 

 the fundamental importance of nitrogen in plant nutrition, however, compara- 

 tively few data appear as to the morphological effects of its absence. In ger- 

 minating moss spores, Schoene ('06) found: "Bei Stickstoffhunger schreitet 

 Funaria zu einer machtigen Ueberlangung des Rhizoidsystems unter voll- 

 standiger Unterdriickung des Chloronemas, die tibrigen Moossporen entwickeln 

 sich zu chlorophyllosen Hemmungsbildungen." Winkler ('13) cited several 

 examples to illustrate the dependence of form upon the quality of food in plants 

 which require organic nutriment (fungi and many algae). No descriptions of 

 cytological changes as a result of nitrogen deficiencies in plants have been found 

 in the literature. Prantl ('81) noted that fern prothallia cultivated in nitrogen- 

 free solutions produce antheridia only (archegonia also appearing in controls on 

 complete nutrient solutions). Dickson ('18) found that in the oat plant the 

 effects of a nitrogen deficit resemble those of a phosphorus deficit, either one 

 severely crippling the development and preventing stooling. The develop- 

 mental period is thereby lengthened and the total dry weight of the plant as 

 well as the grain production is lowered, although the weight of the individual 

 kernels and the ratio of grain to straw appear increased. 



Urbain ('20) obtained some interesting results in numerous plants, including 

 wheat, oats, barley, Mirabilis jalapa, Spinacea cleracea and Pinus pinea. The 

 grains were soaked in water, and at successive intervals of time the embryos 

 were removed from the endosperm (thereby depriving them of their normal 

 organic nutriment, vitamins, etc.), and placed in artificial nutrient solutions. 



