March 31, 1905.] 



SCIENCE. 



483 



to absence of water in the resistant cells, 

 these cells behaving like endospores, al- 

 though not known to be endospores {i. e., 

 from species not known to produce endo- 

 spores). Possibly these resistant cells are 

 to be considered as arthrospores. (6) En- 

 dospores freed from non-sporiferous vege- 

 tative cells by heating in the water-bath 

 for fifteen minutes at 70° C. were not in 

 any way injured by freezing (two species), 

 and this would seem to be an added proof 

 that the protoplasm of such spores is desti- 

 tute of water, a conclusion already reached 

 by various observers on account of their 

 behavior in boiling water and streaming 

 steam. 



So far as any general inference can be 

 drawn from experiments made only in 

 bouillon, we may conclude that bacteria are 

 injured by freezing to very different de- 

 grees, behaving in this respect like the 

 higher plants and animals. Many kinds, 

 like Bacillus typhosus, are destroyed in 

 great numbers even by short freezings, 

 while other forms, like Bacillus sorghi, are 

 rather resistant. The former idea that 

 bacteria in general are not harmed by 

 freezing is untenable. It was based on 

 qualitative tests which are incapable of 

 showing the true state of affairs in the 

 exposed culture. Probably an enormous 

 number of bacteria are destroyed by every 

 winter, and those which survive come 

 through in the form of endospores or some 

 other resistant shape. These experiments 

 confirm and extend those of Prudden, 

 Park and Sedgwick and Winslow. They 

 will be repeated, freezing in water, and will 

 be extended to include some additional 

 species, and will probably be published by 

 the U. S. Department of Agriculture. 



The Viability of B. Dysenterim Shiga: 

 W. D. Frost and R. Whitman, Univer- 

 sity of Wisconsin. 



Four strains of this organism were test- 



ed. One was the Shiga type. The others 

 belonged to the Flexner-Harris type. Of 

 these one was the Harris culture and the 

 others were from Duval and Bassett's 

 series of summer diarrhoea cases. The 

 viability was tested by drying the organ- 

 isms on articles of merchandise, dried food 

 substances and in sterile distilled water 

 and milk, under various conditions. A 

 summary of the conclusions reached fol- 

 lows: the B. dysenterice when dried on 

 articles of merchandise, as paper, cloth and 

 wood, dies rapidly in from four to nine 

 days at the temperature of 17-20° C. On 

 dried food substances, as bread, rice and 

 albumin balls, this germ may live for days. 

 In some cases it is able to live over a 

 month. In sterile distilled water the life 

 of the germ is very short, rarely maintain- 

 ing itself more than a week. In sterile 

 milk the germ can live until the medium 

 is dried up. The different strains vary in 

 their viability under given conditions, the 

 Shiga type culture being distinctly more 

 frail than cultures of the Flexner-Harris 

 type, the effect of temperature in modify- 

 ing the viability of the germ being im- 

 portant. At a temperature of 38° C. it 

 will live from only one half to one fourth 

 of the time that it will live at a tempera- 

 ture of 17-20° C. 



Pseiidomonas Canipestris (Pam.) Smith: 

 H. A. Harding and M. J. Prucha, Ex- 

 periment Station, Geneva, N. Y. 

 Pseiidomonas campestris (Pam.) Smith 

 is a yellow non-spore-forming plant para- 

 site. It attacks cabbage, cauliflower and 

 allied plants by way of their fibrovascular 

 system. 



A study of its resistance to desiccation 

 showed that while it died when exposed on 

 sterile cover-slips for a few days (in our 

 experiments not surviving a ten-day ex- 

 posure), it retained its vitality on cabbage 

 seed for more than a year. Apparently 



