1888.] MICROSCOPICAL JOURNAL. 63 



others the primary trunk and the limbs may contract independently, although 

 in these colonies the movement of the main stem is usually followed by the 

 contraction of one or more of the branches with the attached bodies ( CarcJie- 

 sium\ ; in still another the pedicle is rigid, but the lowermost portion is 

 curved around the object to which it is attached, and acts as a spring to sud- 

 denly sweep the entire organism circularly through the water and back again 

 to the normal upright position, the curved portion having the function of a 

 spring ( Opisthostyla) . 



The methods of reproduction are sufficiently diverse, but in a short paper 

 with the character of the present one they can be only mentioned, leaving 

 details for a future time. In addition to the commonly observed longitudinal 

 division, the methods are by transverse and oblique fission, the encystment 

 of the body, with subsequent subdivision into minute spores, and by the 

 formation of buds which finally become migratory zooids and unite with 

 some mature infusorial body of the same species as their parent, the living 

 combination of animalcule and fertilizing microzooid, at some future time 

 undergoing reproductive fission. In Voi'ticella conjugation of mature forms 

 has occasionally been observed. 



The sheathed, or loricate, members of the family, while they do not attract 

 attention by their movements, as does VorticeUa, or by the beauty of their 

 dendritic pedicles lifting into the surrounding water a wealth of living fruit, 

 yet they are always charming bv reason of the graceful contour or the pecu- 

 liar appendages of the loricae. Hyaline vases and crystalline amphorae, with 

 their anterior aperture open to the water, or protected by a movable valve ; 

 bodies with no protection except the delicate walls of their loricce, or bodies 

 with a chitinous or, fleshy antero-lateral outgrowth, called the operculum, 

 with which the contracted animalcule plugs up the aperture to its home ; 

 all these and others help form the interesting group of the Vorticellid£e. 



The loricae are secreted by the bodies of the enclosed animalcules. The 

 soft and colorless substance forming them has the property of hardening on 

 contact with the water, thus becoming an effectual barrier to danger. When 

 young these sheaths are colorless and transparent as glass ; when mature or 

 old they often become chestnut brown in color ancl sometimes almost opaque. 



Others of the loricate section of the family do not produce loricas in the 

 usual sense of hardened, chitinous enclosures, but protect themselves by the 

 secretion of a soft and jelly-like substance in which they live,. and into which 

 they retreat when danger "threatens. One of these {Opktydhitn) — there are 

 but two, the second being OpJiionella — is not rare in ponds and still waters 

 where the colonies may be found in the form of little green jelly masses adherent 

 to aquatic plants, or floating on the surface as rounded globules, varying in 

 size from that of a pea to that of a walnut ; indeed, immense colonies the 

 size of one's fist have been recorded, but these are uncommon. Ophionella 

 is a solitary creature, erecting its soft sheath on some water-weed away from 

 all of its own species, and never forming social colonies. It is rare in this 

 country, having been observed but once, so far as I am aware. Prof. D. S. 

 Kellicott, of Buffalo, has had the good fortune to find the curious animal in 

 the Niagara river. 



We have thus superficially noted some points in this infusorial family in 

 order, as has been said, to lead the beginner in the study of microscopical 

 pond-life to an easy, and it is hoped, satisfactory identification of the genera 

 comprising the family. To include the species is not practicable in the 

 limited space of a single paper. 



The following key is to be used as all similar analytical tables are used. 

 A good half-inch objective is probably sufficient for the purposes of identifi- 

 cation ; a quarter-inch will be amply sufficient. 



