CHAPTER XXV. 

 ANAEROBIC BACTERIA. 



BACILLUS TETANI. 



THE infectious nature of tetanus was first clearly demonstrated by 

 inoculating rabbits subcutaneously with pus from a human case of 

 the disease. This experiment, which reproduced the essential clinical 

 features of the disease and killed the animals, was performed by Carle 

 and Rattoni 1 in 1884. The same year Nicolaier 2 saw the tetanus 

 bacillus in laboratory animals which were inoculated subcutaneously 

 with garden soil, at the site of injection. It remained for Kitasato, 3 

 however, to grow the tetanus bacillus in pure culture and to definitely 

 transmit the disease to laboratory animals through pure cultures of 

 the organism. 



Morphology. Bacillus tetani is a long, slender bacillus with rounded 

 ends, measuring from 0.3 to 0.8 micron in diameter and from 2 to 5 

 microns in length, which commonly occurs singly and in pairs in young 

 cultures; in older cultures the organisms tend to form long chains. 

 It tends to degenerate in older cultures, leaving free spores and involu- 

 tion forms. The bacillus is slightly motile in recently inoculated 

 cultures and possesses from sixty to eighty peritrichic flagella. 4 Cap- 

 sules are not produced by Bacillus tetani. It stains readily with 

 ordinary dyes and is Gram-positive. Spores are readily formed under 

 anaerobic conditions, which are so characteristic in appearance and 

 constant in occurrence that they are of diagnostic importance. The 

 spores are spherical, greater in diameter than the bacillus (measuring 

 1 to 1.5 microns in diameter) and occur at one end of the rod, giving 

 it the appearance of a drumstick or plectridium. The rate of spore 

 formation in artificial media appears to be greatly influenced by the 

 temperature of incubation: at 20 C. spores appear in from seven to 

 eight days; at 37 C. they are usually found in large numbers after 

 one to two days; at 43 C. the organisms grow slowly and form but 

 few spores; but little toxin is produced at this temperature. 



1 Giornale della R. accad. di med. di Torino. 



2 Deutsch. med. Wchnschr., 1884, No. 52; Inaug. Diss., Gottingen, 1885. 



3 Deutsch. med. Wchnschr., 1889, No. 31; Ztschr. f. Hyg., 1889, vii, 225. 

 "Schwarz, Lo sperimentale, 1891, p. 373. Grandi, Centralbl. f. Bakt., Orig., 1903, 



xxxiv, 97. 



