Bacteria 37 



Endospores, or spores developed within the cells, are gen- 

 erally formed in the elongate bacteria, bacillus and spiril- 

 lum, 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 



a b c d e } 



O o (3^=> 



Fig. 1. Diagram illustrating sporulation: a, Bacillus inclosing a 

 small oval spore; b, drumstick bacillus, with the spore at the end; c t 

 clostridium; d, free spores; e and /, bacilli escaping from spores. 



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 distending 

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

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

 of anaerobic bacilli. When the formation of a spore is 

 about to commence, a small bright point appears in the 

 cytoplasm, and increases in size until 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 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. Von Szekely* found 

 anthrax spores capable of germination after eighteen years 



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



