Reproduction 33 



The spores differ from the bacteria in that their capsules 

 prevent evaporation and enable them to withstand drying 

 and the application of a considerable degree of heat. Very 

 few adult bacteria are able to. resist temperatures above 

 70 C. Spores are, however, uninjured by such temper- 

 atures, and can even successfully resist the temperature of 

 boiling water (100 C.) for a short time. The extreme 

 desiccation caused by a protracted exposure to a dry tem- 

 perature of 150 C. will invariably destroy them, as will also 

 steam under pressure. Not only can the spores successfully 

 resist a considerable degree of heat, but they are also un- 

 affected by cold of almost any intensity, and the duration 

 of their vitality is very remarkable. Von Szekely * found 

 anthrax spores capable of germination after eighteen years 

 and six months in some dried-up old gelatin cultures found 

 in his laboratory. 



Arthr os pores. The formation of arthros pores is less clear, 

 and seems to be the conversion of the entire organism into a 

 spore or permanent form. Arthrospores have been observed 

 particularly among the micrococci, where certain individuals 

 become enlarged beyond the normal, and surrounded by a 

 capsule. Hiippe, who has paid particular attention to the 

 arthrospores, believes that they have resisting powers far 

 greater than those possessed by the bacteria themselves. Of 

 the arthrospores little has, so far, been learned. It is not 

 improbable that among the micrococci, and also among some 

 of the smaller bacilli in which no spores have been observed, 

 the maintenance of the species when conditions of life become 

 unfavorable is due to the assumption of a permanent form 

 by some of the individuals, without the formation of any 

 spore-like bodies. 



Though the cell-wall of the adult bacterium is easily pen- 

 etrated by solutions of the anilin dyes, it is difficult to stain 

 spores, which are distinctly more resistant to the action of 

 chemic agents than the bacteria themselves. 



Germination of Spores. When a spore is about to germi- 

 nate, the contents, which have been clear and transparent, 

 become granular, the body increases slightly in size, the 

 capsule becomes less distinct, and in the course of time 

 splits open to allow the escape of a young organism. The 

 direction in which the capsule ruptures varies in different 

 species. Bacillus subtilis escapes from the side of the spore ; 

 Bacillus anthracis from the end. This difference can be 

 3 * "Zeitschr. fur Hygiene," 1903, XLIV, 3. 



