496 SYSTEMATIC HISTORY OF THE INFUSORIA. 



Genus BODO (XVIII. 9). — The caudal appendage at the posterior extremity 

 of the animalcules is a decisive character of the genus ; mouth terminal, fur- 

 nished with a (single ?) filament ; self-division simple and complete ; eye- 

 speck absent. They never constitute true or perfect clusters like some of 

 the family Monadina, although, like Uvella, they occasionally aggregate. In 

 B. grandis, several vacuoles have been observed, and (as also in B. intestinalis) 

 a simple (perhaps double ?) filament. B. cUdymus has been known to divide 

 transversely. 



This genus Bodo partly comprehends the genera Hexamita, AmphimonaSy 

 and Cercomonas of Dujardin, which are, with others, introduced as addenda 

 to this family Monadina. Dr. Burnett has made the following very correct 

 and just remarks on this genus Bodo and its division into species : — 



"The tailed Monads or Bodos are found in the intestines of the common house- 

 fly or in those of the frog. Those from the fly, when fii^st seen, resemble in shape 

 a kernel of rye, and are about 1- 6000th of an inch in breadth, and 1 -2000th 

 in length. Attached to the body is a delicate hair-like tail, four or five times 

 its length. By the addition of water, the body enlarges by endosmosis, as- 

 suming a perfectly spherical shape after passing thi^ough all the intermediate 

 ones, so that, when magnified by the highest power of Spenser's microscope, 

 it is nearly one inch in diameter, permitting the most thorough and satisfac- 

 tory study of their structure, which I find, after repeated observations, has 

 no peculiarities except those belonging to cells. It is a closed cell sac, mth 

 a filiform caudate process, and capable of the actions of cell-membranes, viz. 

 endosmosis and exosmosis. In the interior of this sac are found sometimes 

 a few granules and sometimes a nucleus. 



" In the Bodos of the frog, which are larger, I have seen distinctly, in some, 

 a nucleus with a nucleolus, in others two nuclei, and in others still, four 

 nuclei of equal size, thus showing that here the multiplication of cells takes 

 place, as elsewhere, by segmentation of the nucleus. 



" Apart from these characteristics, which are insufiicient, the fact that I 

 have sometimes met with them in the interior of epithelial cells, would be 

 strongly presumptive of their cell origin from minute granules that pass 

 through the cell-waUs. The representatives of the genus Bodo therefore 

 appear to be simple cells, each with a filiform appendage for locomotion, and 

 which locomotion, therefore, can have no adaptive character. 



" There are differences in them as they may be taken from different locali- 

 ties ; but, because these particles are cell.^ capable of much change by dilata- 

 tion and contraction, these differences can never serve as the basis of species, 

 which would also be true from the fact that, having no individuality of their 

 own, there is necessarily no absence of type characteristics." 



Bono intestinalis (xviii. 9). — Almost 

 conical, transparent, and colourless ; tail 

 of equal length with the body. Found 



in several living animals, such as fi'ogs 

 and toads. Amongst the watery mucus 

 of the alimentary canal Ehrenberg has 

 observed great numbers of these crea- 

 tures, and remarks that the Cercaria 

 Gyrinus of MiiUer (a different animal- 

 cule) might pass as a representation of 

 this species, and that it was confounded 

 by its discoverer with Spermatozoa. 

 1-1720". 



B. ranarmn(= Cercomonas Ranarum, 

 Perty). — Body turgid, ventricles indi- 

 stinct. In live frojj's, with the preceding 



species, and with the Bursaria ranarum. 

 1-1440". 



B. viridis. — Green, nearly globular,; 

 tail very short. Amongst Confervae. 

 1-2400". Perty believes this species to 

 be merely the young of Euylena viridis. 



B. socialis {3Ionas Lens, M.). — Ovate 

 or subglobose ; tail often longer than the 

 body ; transparent and colourless. Clus- 

 ters in a mulberry shape. Single forms 

 are sometimes observed hopping. Com- 

 mon in stagnant water. 1-2970". 



B. vorticellaris (= Cercomonas, Perty). 

 — Body three times as long as it is 

 broad ; tail verv short. In fresh water. 

 1-11200". 



