188 GENEEAL HISTORY OF THE INTUSOEIA. 



contain other Algae, and especially the common Torula; for I do not re- 

 member to have seen the Torula without Vibrionia.^' 



Perty moreover testifies to Vibrio Bacillus assuming a still condition, and, 

 by its branching concatenation, a plant-like form, out of which are constructed 

 masses and films in the infusion and upon its surface, resembling Hygro- 

 crocis and other Algae and aquatic Fungi. 



Dr. Ayres {J. M. S. i. p. 301) contributes the following obsei^vations on 

 the self-division of the Vib/ioma : — " A\Tiile," he writes, " the shortest of the 

 Vibriones were in active motion, the longer ones were comparatively quies- 

 cent ; and these exhibited, according to their length, from one to six trans- 

 verse lines, indicating the points of separation in the reproductive process. 

 Those of moderate length, presenting only one or two transverse hnes, were 

 rather active, and often bent at an angle at the transverse lines, which pre- 

 sented the appearance of separation into two distinct indi\iduals ; and the 

 character of the movements appeared such as to favour the separation. Those 

 with fi'om three to six transverse lines were, for the most part, quiescent. 

 I imagined, although from their excessive minuteness and transparency this 

 was not plainly and unequivocally discernible, that there were indentations 

 of the extremities of the transverse Hnes, by which constrictions were pro- 

 duced, which, by their increase, would finally efi'ect a complete transverse 

 division of the animals." 



The occurrence of Vibrios, or at least of Vibrio-]jke forms, as one of the 

 metamorphic phases of the Pliytozoa of the antheridia of Characece, e.g. 

 Marchantia, has been mentioned in a foregoing page (126), to which we 

 must refer our readers. 



FAMILY v.— ASTASI^A OE EUGLEN^A. 

 (Plate XYIII. 36—50, 62, 53, 55, m.) 



Dujardin very properly prefers to caU this group Euglencea {Eugleniens), on 

 account of the resemblance in sound of the fii^st name with that of Astacicea 

 (Astaciens) used to designate a family of the higher Crustacea. 



In Ehrenberg's system it constituted a family of the Polygastrica, and was 

 characterized by wanting a tnie alimentary canal, a lorica and appendages, 

 and by having a mouth sm^mounted by one or two proboscides, and in most 

 species by a changeable form. Internally, digestive sacs, ova, a seminal gland, 

 and contractile vesicle, and in most genera one or more red specks or eyes, 

 were represented as present. The genera included were — Astasia, Ambly- 

 oj)his, Euglena, Chlorogonium, Colacium, and Distigma. The value of these 

 genera has been called in question by various wiiters. Dujardin makes the 

 variability of form — in other words, a contractile integument — a leading fea- 

 ture, and rejects the eye-speck as neither distinctive nor constant ; conse- 

 quently he excludes from the family the EugUnce with rigid integument, 

 and transplants them to the Thecamonadina, and rearranges the remaining 

 species according to the number, disposition, and character of theii' locomo- 

 tive filaments. Likewise Schneider (A. iV. H. 1854, xiv. p. 327) separates 

 Chlorogonium from the Astasia^a because of its unchangeable figure ; and 

 Mr. Carter {A. N. H. 1856, xviii. p. 116) would also detach Astasia from Eu- 

 glena, from the conviction that the former has an animal organization, and 

 that the latter is referable to plants. 



In the follo^ving general history of the Astasicea, our descnption will 

 chiefly apply to the two genera Astasia and Euglena, respecting which we 

 have very copious details in the papers by Mr. Carter, (A. N. H. 1856, xviii.). 



