40 BACTERIA. 



The Spiro-bacteria vary very much, not only in size but also 

 in length and in general appearance. 



In some instances other isolated features have determined a 

 nomenclature. For example, the appearance of sulphur 

 in one series of forms has determined a species of Ophido- 

 monades ; whilst the form and length of curves have also been 

 used as a distinguishing feature. The organism is spoken of as 

 a Vibrio when the curves are slightly marked ; if the curves 



Photo-micrograph of Bacillus Figuraus in which Leptothrix form is 

 well seen, x 150. 



are short and slightly pronounced and the organism is thin 

 it is known as a Spirochasta ; a ribbon-shaped spiral is a 

 Spiromonad, and a spindle-shaped spiral, a Spirulina. 



CORN'S CLASSIFICATION. 



ScMzopkytes, Thallophytes that develop by division or by 



endogenous germinating cells. 



