SPIRILLUM (SPIROCH^ETE) OBERMEIERI. 481 



All the other spirilla are as yet very incompletely incompletely 

 known, and we do not possess methods of cultivating 

 them in a state of purity, and of observing their mode of 

 development. They appear to grow by preference on 

 fluid substrata, and to accumulate more especially at the 

 surface ; a situation in which they are usually found in 

 enormous numbers is in the ordinary cesspools (Miihl- 

 hauser). Besting forms have not as yet been described 

 with certainty in the majority of the species which have 

 been observed, the only exception being spirillum rugula; 

 but it is possible that at a future period spore-like struc- 

 tures will be found in other of the bacteria belongiDg to 

 this almost unknown class. 



Geddes and Ewart* state that they have observed the 

 following facts as regards the mode of development and spore 

 formation of spirilla; the spirilla have alternately a motile 

 :ind a resting stage ; they ultimately grow in the form of a 

 small thread without any definite coils ; this thread becomes 

 longer and thicker, and spores appear in it. These spores 

 divide rapidly and become glistening and brown, while the 

 threads become again motile and break up sooner or later. 

 The spores thus liberated become encysted, and divide into a 

 number of capsules which become motile after a period of 

 rest ; the " sporulas " contained in the capsules escape, sprout 

 in a comma form, and soon grow to the ordinary spirillum. 

 These observations have evidently not been made on pure 

 cultivations, and are of no value. 



The following are the spirilla which have as yet been 

 distinguished from one another, but which require more 

 accurate study: 



Spirochate plicatilis. Threads thin with numerous 

 narrow turns, 110 to 

 *225 fi. in length. As 

 a rule the threads form 

 a double wavy line ; 

 the primary turns are 

 of the same size in all A 



the examples; the se- ^ Spiroch{fite pu^gu^^ in its * elgh . 



COndary turns are bourhood vibrio rugula (a) and other 



, , . bacteria. 



Otten Unequal in Size. B, Spirochsete from the teeth X 500. 



The ends are blunt. The organism moves with extreme 



* Proc. of the Roy. Soc. t vol. 27, p. 481. 



81 



