OF THE PHYTOZOA. 185 



filament, and spontaneous fission. Of the Vihrionia generally, he stated that 

 they were unable to change the form of their body, although without lorica, 

 and that by imperfect self-division they formed chains or concatenated fila- 

 ments, which in S_pirillum, from the obhquity of the junction-siufaces of the 

 component Vibrios, assume a spiral form. 



Yarious later writers, among whom are Leuckhart, Cohn, and Burnett, 

 would transfer the Vihrionia to the vegetable kingdom. The last-named 

 author contributed a valuable paper to the American Association in 1850 ; 

 but the most recent examination of the nature and structure of the beings in 

 question is from the able pen of Dr. Cohn (Entw.). "We must also mention 

 that Perty has given considerable attention to the Vihrionia, and contributed 

 some original observations. It is to Cohn's account, however, that we shall 

 chiefly resort in oiu' attempt to describe the minute and ciuious members of 

 this family, which, if not rich in genera, is unsurpassed by any in the abun- 

 dance and diffiision of its members. 



Some natiu'alists have considered the Vihrionia to be the active agents in 

 producing putrefaction, since they are invariably found in decomposing fluids, 

 just as the yeast-plant (Torida) always occurs in fermenting saccharine mat- 

 tei*s and appears to excite the process of fermentation. 



The Vihrionia are for the most part colourless ; imder certain conditions, 

 however, they assume a yellow, red, or a blue tint, but never a green colour'. 

 Their movements, says Perty, are rapid and energetic, so much so that the 

 corpuscles of Hysginum nivale, although at least one thousand times larger, 

 are thinst aside by Bacterium Termo when in motion. They can advance 

 with either end forward with equal facihty, and mostly seem, after proceed- 

 ing a certain distance, to retrace their course to the point they started from. 



The extreme minuteness of some Vihrionia may be conceived from the 

 statement of Perty, that, according to his calculation, four thousand millions 

 occupy no more space than one cubic line. 



Dujardin, who retains the Vihrionia among animalcules, makes the follow- 

 ing remarks : — " The Vihrionia are the first Infusoria which present them- 

 selves in aU infusions, and which from their extreme smallness, and the im- 

 perfection of our means of observation, must be considered the most simple ; 



for it is only their more or less active movements which lead to their 



being regarded as animals at all. I have been sometimes induced to beheve 

 that there is a flageUiform filament, analogous to that of monads, or rather 

 perhaps a spiral undulating one, which produces the peculiar mode of loco- 

 motion. Is the Bacterium triloculare, described by Ehrenberg as having a 

 proboscis, a true Vihno ? 



" AU that can be with certainty predicated respecting their organization is 

 •that they are contractile, and propagate by spontaneous fission, often imper- 

 fect in character, and hence give rise to chains of greater or less length." 



Cohn modestly premises {Entw. p. 118) that his researches have been di- 

 rected chiefly to one species ; yet, from scattered observations, and fi^om pre- 

 sumptive evidence, he would assign a vegetable nature to aU the species. 



In decomposing infusions, often after a few hours, extremely minute 

 corpuscles may be seen in countless number, having the figm^e of a dot or 

 comma, or of very delicate hues with the ends somewhat thickened. Their 

 motion is tolerably active, darting hither and thither, contorting themselves 

 at the same time by a rotating movement upon their long axis, and, when in 

 masses, produce the appearance of a ceaseless swarming, in which the indi- 

 vidual specks are easily overlooked on account of their smallness. They, 

 however, differ in size among themselves, varying from 1-2000 to 1-700'" in 

 length. Ehrenberg attributed to this world-wide form the name of Vibrio 



