340 Dr. W. C. Sturgis. A Soil Bacillus 



change whatever was detected in the elastic condition of the material ; 

 the process of recovery seemed to be neither accelerated nor retarded. 



For the compression experiments described in the paper, an instru- 

 ment, specially designed by Professor Ewing, was employed to measure 

 the small compressional strains. By the aid of this instrument, the semi- 

 plasticity of recently overstrained iron was readily observed, and the 

 effect of moderate temperature in restoring elasticity was demonstrated 

 by means of compression tests. The lowering of the compression yield- 

 point which accompanies the raising of the tension one (due to tensile 

 overstrain) was also clearly shown. This lowering, however, was not 

 found to be such as to keep the total range of elasticity for the 

 material constant ; that is, the lowering of the compression yield-point 

 was not found to be equal to the raising of the tension one. 



In conclusion, the characteristics of overstrained iron are considered 

 as illustrating Maxwell's views on the " Constitution of Bodies," as 

 set forth by him in the ' Encyclopaedia Britannica.' 



" A Soil Bacillus of the Type of De Bary's B. megatherium" By 

 W. C. STURGIS, M.A., Ph.D. Communicated by Professor H. 

 MARSHALL WARD, F.B.S. Keceived January 27, Piead 

 February 9, 1899. 



(Abstract.) 



The organism which forms the subject of these investigations was 

 isolated from clayey and gravelly soil, at a depth of about an inch 

 below the surface. It is a straight, or slightly curved bacillus of rather 

 large size, measuring 3'4 7 -7f* x 1-2 1'fyf, and occurs either as 

 isolated rods or in the form of long chains. Its peculiar interest lies 

 in the fact of its marked predilection for acid media, and its behaviour 

 in the presence of carbohydrates. It also offers peculiar advantages 

 for the study, by direct observation in hanging drops, of the formation 

 and germination of the spores, the formation of gelatinous sheaths, the 

 co-existence of motile and non-motile stages, and the rejuvenescence of 

 so-called involution forms, the former process especially being very 

 rapid under suitable conditions. 



The organism forms on solid, acid media, such as saccharose-gelatine, 

 large, domed, translucent drops, consisting of chains of rods provided 

 with thick, firm, and gelatinous sheaths. The latter character is 

 exhibited only in media containing carbohydrates, especially cane sugar ; 

 in media devoid of carbohydrates the colonies are slimy rather than 

 gelatinous, and consist of almost naked rods and chains. Moreover, 

 even in the presence of sugar, the formation of an investing sheath is 

 largely dependent upon the age of the culture, the vigour of the 



