36 ECOLOGY, PLANT GEOGRAPHY [Bot. Absts., Vol. IV, 



fluence of the invading fungus. The morphology of the infected host tissues and also that 

 of the invading mycelium is presented in considerable detail. Microchemical studies showed 

 that the walls of the invaded host cells become lignified as a specific reaction to the infection. 

 These "Rhizothamnien" occur on all roots of Casuarina equisetifolia growing on its native 

 habitat, but they were entirely absent from plants grown under greenhouse conditions in the 

 botanical garden at Leipzig. The author compares the inter-relation of fungus and host in 

 this particular instance with other mycorhizal relationships which have received careful 

 study. He believes this to be a case of typical symbiosis in which the fungus may be of use 

 to the host plant in working over nitrogenous materials derived from the humus of the soil 

 into such forms as can be used directly in the metabolism of the plant. — P. D. Strausbaugh. 



249. Nakajima, Y6z6. Midzu-ohbako no kwajitsu no hokwai gensho ni tsuite. Ueber 

 das Verbreitungsmittel der Samen von Ottelia alismoides Pers. [On the method of seed dis- 

 semination of Ottelia alismoides Pers.] [Title in Japanese and German, text in Japanese.] 

 Bot. Mag. Tokyo 33: 44-52. Mar., 1918. — The fruit of Ottelia alismoides discharges its seeds 

 after it has floated up to the water surface or while rising to the surface. Dissemination takes 

 place by means of a special disintegration of the fruit shell, in which the component cells 

 become dispersed in the water. This disintegration can be hindered or stopped if the tissue 

 is placed in a 20 per cent aqueous cane-sugar solution or in a 2 per cent KOH solution. It is 

 concluded that this effect may be due to the lowering of turgor in the cells of the fruit tissue 

 — K. Morita. 



250. Narasimhan, M. J. A preliminary study of root-nodules of Casuarina. Indian 

 Forester 44: 265-268. June, 1918.— See Bot. Absts. 1, EDtry 1454; 3, Entry 111. 



251. Neger, F. W. Die Wegsamkeit der Laubblatter fur Gaze. [Gas passage-ways in 

 leaves.] Flora 11-12: 152-161. 1918. — A comparison of different leaf types as to their aera- 

 tion systems, and the degree of connection between intercellular spaces. — See Bot. Absts. 2, 

 Entry 619.— H. C. Cowles. 



252. Nelson, J. C. Flowers of varying color. Amer. Bot. 25:96-99. 1919.— Forty- 

 nine flowers that have different color forms, 43 that have two or more colors in their blossoms, 

 and 8 that change color in blooming are listed. — W. N. Clute. 



253. [Nordstedt, C. F. O.] [Swedish rev. of : Hesselm an, H. Iakttagelser over skog- 

 stradspollens spridningsformaga. (Observations on the dispersal capacity of forest tree pollen.) 

 Meddel. Statens Skogsforsoksanstalt 16: 27-60. S fig. 1919. See Bot. Absts. 4, Entry 232.] 

 Bot. Notiser 1919: 167-168. 1919. 



254. [Nordstedt, C. T. O.] [Swedish rev. of: Resvoll, T. R. Om planter som passar 

 till kort og kold sommer, 884 V- No date on citation given. Regarding plants which are fit 

 for a short and cold summer]. Bot. Notiser 1918: 139-140. 1918.— P. A. Rydberg. 



255. Osterhout, W. J. V. Endurance of extreme conditions and its relation to the theory 

 of adaptation. Amer. Jour. Bot. 5: 507-510. Fig. 1. Dec, 1918. — A species of Tradescantia 

 (T. fluminensis?) is found to resist equally extremes of drought and of moisture. Pieces of 

 this plant lying on the laboratory table, deprived of soil and all sources of moisture supply 

 except the air continued to live and grow for nearly two years. They lost from 10.5 to 95 per 

 cent in weight but increased as much as 150 per cent in length. Subsequently these same 

 pieces planted in soil in a saturated atmosphere grew vigorously and normally. Even when 

 submerged in running water, some of them remained alive and grew slightly for the period 

 of one month when the experiment was discontinued. The author believes that "the expla- 

 nation of such cases must be sought in physical or chemical conditions of the protoplasm 

 which arise without reference to direct adaptaton" and "that many cases now regarded as 

 adaptation may prove to be fictitious." [See Bot. Absts. 2, Entry 1128.] — P. D. Straiisbaugh. 



