VIBRIONIA. 103 



family Ftbrionia, for the minute beings which 

 form it are very difficult to examine, on account of 

 their small size, many of them being invisible to 

 microscopes of low power. If it were not for the 

 circumstance of their linking together, so as to 

 form threads, they would escape our observation. 

 Sometimes two or three individuals only, form 

 the chain or thread, at others a greater number, 

 and from this circumstance it is supposed that 

 they are originally separate, and only join together 

 for mutual support, or that it is caused by the 

 imperfect method of self-division. One genus, 

 Bacterium, has a tremulous motion, but looks 

 like a very fine stiff thread : it requires a power 

 of more than 500, to see the individuals of 

 which it consists. The genus Vibrio is more 



