June 18, 1897.] 



SGIENGE. 



963 



siuni hydroxide on alumiuum sulphate have, 

 however, led to the conclusion that the act is 

 not entirely a mechanical one, but that it is a 

 phenomena of strictly chemical nature. In 

 the present paper the author has undertaken 

 a study of the action in the case of iron hydrox- 

 ide. While the results are not sufBcient to 

 definitely establish the nature of the action, they 

 are inconsistent with the theory of mechanical 

 inclusion and characteristic of chemical action. 

 Reviews of the following books are also con- 

 tained in this number of the journal : 



'The Constants of Nature,' F. W. Clarke, 

 Part v.; ' The Chemistry of Dairying,' N. Sny- 

 der ; ' Inorganic Chemical Preparations,' F. H. 

 Thorp; ' Traite Elementaire de Chimie,' Hal- 

 ler et MuUer ; ' The Principles and Practice of 

 Agricultural Analysis,' H. W. Wiley, Vols. I., 

 II. and III.; 'Vorlesungen iiber Bildung und 

 Spaltung von Doppelsalzen,' J. H. Van't Hoff ; 

 ' An Outline of the Theory of SolutioBs and Its 

 Eesults,' J. L. R. Morgan. 



J. Elliott Gilpin. 



SOCIETIES AND ACADE3IIES. 



BIOLOGICAL SOCIETY OF WASHINGTON, 27STH 



MEETING, SATURDAY, MAY 22. 



Dr. Erwin F. Smith described ' A Bacterial 

 Disease of Cruciferous Plants,' illustrating his 

 remarks by means of drawings, diseased plants, 

 and cultures of the organism on various media. 

 The parasite is a yellow germ and is considered 

 identical with that isolated by Professor L. 

 H. Pammel from rotting turnips. Nearly all 

 of Pammel's statements are confirmed, and 

 much new information has been obtained con- 

 cerning pathogenesis, symptomatology, host 

 plants, manner of infection, thermal relations 

 of the organism and its behavior in a variety 

 of media. The organism was isolated from 

 Maryland turnips and Wisconsin cabbages and 

 a parallel series of cultures and experiments 

 instituted. The following plants have been 

 artifically infected : Cabbage, kale, cauliflower 

 turnip, rape, black mustard, and radish. The 

 dissemination of the disease is probably due in 

 great measure to insects. It has been trans- 

 mitted in the greenhouse from diseased to 

 healthy plants by means of slugs {AgrioUmax 



agrestis) and also by means of the common cab- 

 bage worm (larvas of Plusia brassicw). The 

 organisms show a marked preference for the 

 vascular system of the plants, and a blackening 

 of the veins of the leaves and of the vascular 

 bundles of the stem is a prominent symptom. 

 The vessels become crowded so full of the 

 germs that they may be said to be plugged 

 solid. The interior of the turnip rots, and the 

 cabbage loses many leaves and fails to produce 

 any head. The disease is widespread and 

 well known to market gardners. The organism 

 is rod-shaped, motile, ajrobic ; it does not pro- 

 duce gas or acid ; it liquefies gelatin ; it grows 

 rapidly at room temperature (20° to 26° C), 

 especially on potato. It grows feebly at blood 

 heat, and will not grow in the thermostat at 

 40° C. The thermal death point is approxi- 

 mately 51° C. It produces a brown pigment 

 when grown on slices of turnip, but not when 

 cultivated on potato or in beef broth. 



Dr. B. T. Galloway spoke on ' the Effects of 

 Environment on Host and Parasite in certain 

 Diseases of Plants.' 



It was stated that plants in their growth and 

 development are controlled by two sets of factors, 

 namely, inherited disposition acting from within 

 and external influences acting from without. 

 Around these factors are centered many com- 

 plicated phenomena, and the object of the paper 

 was to call attention to some of these in their 

 relation to certain physiological and pathological 

 problems. The statements in the main refer to 

 cultivated plants, for in dealing with them in 

 questions, such as those under consideration, 

 conclusions could not be drawn from the be- 

 havior of wild species, except in the most gen- 

 eral way. In other words, one of the funda- 

 mental tenets of agricultural and horticultural 

 practices is that the occurrence and behavior of 

 native plants in any given region is not in itself 

 sufficient evidence to prove that cultivated 

 forms may be successfully grown there. Purely 

 local conditions may make the difference be- 

 between success and failure in growing the 

 crop, and the effects of these conditions must be 

 determined by observations and experiments on 

 the plant itself. 



The effects of environment on the host and 

 the possible changes in the life processes as a 



