334 TEXT-BOOK OF BACTEEIOLOGY. 



develops only in persons having in some wa^' come in contact 

 with horses. 



The tetanus bacillus is a large, slender rod, with rounded ends, 

 frequently forming long threads, showing distinctly the separating 

 points of the single members. Sporulation (as already said) takes 

 place in the ends of the rods, this part of the cell swelling up like a 

 drum-stick and developing the form of music notes or pins. Spor- 

 ulation takes place in thirty hours at breeding temperature and in 

 about a week at room temperature. The tetanus bacillus is motile; 

 it grows at common and breeding temperatures (better in the lat- 

 ter) and belongs to the strictly anaerobic species, since it not 

 oulj- does not thrive in contact with the oxjgen of the air, but even 

 perishes quickly so that the rods in the haiiging drop, for instance, 

 very rapidly lose their capacity of voluntary motion. 



The rods are readily accessible to staining. Gram's method is 

 also available. The spores may be made visible in the usual manner. 



On the gelatin plate, in an atmosphere of pure hydrogen, small, 

 radiating colonies slowly arise, which gradually liquefy the gelatin. 

 Under the microscope they appear as dense, flrmlj'-compacted 

 masses with a delicate border bearing numerous very delicate proc- 

 esses and ciliate filaments — a picture resembling that of the hay- 

 baciUus. 



The puncture culture in grape-sugar gelatin presents a 

 strange sight. The upper parts of the medium remain sterile, but 

 deeper the inoculation puncture is surrounded by a rapidly-increas- 

 ing bacterial proliferation, sending out thousands of small, pointed 

 shoots into the sutrounding medium, so that the culture, in this stage 

 of development, toward the end of the first week, looks like "a wide- 

 branched fir-tree and resembles a young brood of the root bacillus. 

 The liquefaction of the gelatin follows later; it causes the delicate 

 detail of the growth to disappear and gradually progresses until 

 finally the whole medium is involved, which then becomes a turbid, 

 whitish-gray, viscid, and slimy mass. 



The growth in deep agar at breeding temperature is considera- 

 bly more rapid and luxuriant. In twenty-four to forty-eight hours 

 a culture, nearly reaching the free surface, develops in which an 

 abundant formation of gas is noticed, which has a pecuhar unpleas- 

 ant, if not putrid, odor, characteristic of the tetanus bacilli. 



In grape-sugar bouillon, the development is particularly ener- 

 getic, causing at breeding temperature so considerable a production 

 of gas that the flasks, if tightly closed, are sometimes burst and 

 shattered. 



On transmitting a small amount of such a culture to a suscepti- 



