Bacteria 33 



formed in the elongated bacteria — bacillus and spirillum — but Zopf 

 has observed similar bodies in micrococci. Escherich also claims 

 to have found undoubted spores in a sarcina. 



Spores may be either round or oval. As a rule, each organism 

 produces a single spore, which is situated either at its center or at its 

 end. When, as sometimes happens, the diameter of the spore is 

 greater than that of the bacillus, it causes a peculiar barrel shape 

 bulging of the organism, described as Clostridium. When the dis- 

 tending spore is at the end, a " Trommelschlager," or "drum- 

 stick," is formed. End-spores are almost characteristic of anaerobic 

 bacUli. When the formation of a spore is about to commence, a 

 small bright point appears in the cytoplasm, and increases in size 

 untU its diameter is nearly or quite as great as that of the bacterium. 

 A dark, highly refracting capsule is finally formed about it. As soon 

 as the spore arrives at perfection the bacterium seems to die, as if its 

 vitality were exhausted. 



The spores differ from the bacteria in that their capsules prevent 

 evaporation and enable them to withstand drying and the applica- 

 tion of a considerable degree of heat. Very few adult bacteria are 

 able to resist temperatures above 7o°C. Spores are, however, 



a b c d e f 



C°5 <l o) O 00 CS=) @=P 



Pig. I. — Diagram illustrating sporulation: a, BaciUus inclosing a small oval 

 spore; 6, drumstick bacillus, with the spore at the end; c, Clostridium; d, free 

 spores; e and/, bacilli escaping from spores. 



uninjured by such temperatures, and can even successfully resist 

 the temperature of boiling water (ioo°C.) for a short time. The 

 extreme desiccation caused by a protracted exposure to a dry 

 temperature of iSo°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 unaSected by 

 cold of almost any intensity. 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. 



Arthrospores. — The formation of arthrospores 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. 



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

 by solutions of the anilin dyes, it is difficult to stam spores, which are 

 distinctly more resistant to the action of chemic agents than the 

 bacteria themselves. 



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



