233 



INFUSORIA. 



INFUSORIA. 



21 



20. The Injusoria possess a comparatively long life. 



21. As the pollen of the pine falls yearly from the clouds, in the 

 form of sulphur rain, so do the much smaller animalcules appear 

 (from being passively elevated with the watery vapour) floating in a 

 live state in the atmosphere, and sometimes perhaps mixed with 

 dust. 



22. In general the Infusoria maintain themselves pretty uniformly 

 against all external influences, as do larger organised bodies. It is 

 true that they sometimes consume strong poisons without immediate 

 injury, but not without an after-effect. 



23. The weight of the invisible Infusoria, light as it is, is yet 

 calculable, and the most gentle current of air or draught can play 

 with their bodies as with the vapour of water. 



24. The evident and great quickuess of the motion of Infusoria is 

 reducible as follows : Ilydatina senta moves 1-1 2th of an inch in 

 4 seconds, Manas punctum the same in 48 seconds, while JVavicula 

 yracUis takes 26 minutes and 24 seconds- to progress the same 

 distance. 



25. Linnams said ' omnis calx e vermibus :' either to maintain or deny 

 'omnis silex, onme ferrumve, vermibus,' would be at the present moment 



'26. The direct observations as yet known, upon the theory of 

 'generatio primitiva,' are wanting in necessary strictness. Those 

 observant who profess to have seen the sudden origin of the minutest 

 Infusoria from elementary substances, have quite overlooked the 

 compound structure of these organic bodies. 



27. The frequent wonderful changes of form of many Infusoria 

 are yet to have th"ir limits, and the laws governing them defined. 



28. The power of infusorial organisation is instinctively shown by 

 the strong chewing apparatus, with teeth, which they possess, and 

 their exhibition, likewise of a complete mental activity. 



29. The study of Infusoria has led to a more distinct and con- 

 elusive notion of animal organisation generally, and the limits which 

 circumscribe the animal form, from which all plants and minerals, 

 that want the animal organic system, are distinctly separated. 



80. Finally, it results from these inquiries, that experience shows 

 an unfathornableness of organic creatious, when attention is directed 

 to the smallest space, as it does of stars, when reverting to the most 

 immense. 



Under the class Infusoria Ehrenberg embraced two very different 

 forms of animal life. This he did not fail to apprehend, and he 

 divided them into Polyyastrica and Rotifera. The latter division 

 included the animals known by the name of Wheel Animalcules. 

 The Polygastrica, so-called from the supposition that the typical 

 forms possessed a number of stomachs, included all the remaining 

 species of Infusoria. 



Subsequently to the first publication of his views, Ehrenberg 

 separated from what he calls the true Infusoria several families of 

 animalcules which were formerly included in the same class. The 

 principal genera thus separated are Spermatozoa, Cercaria, and Vibrio, 

 which are now considered by some as part of the class Entozoa, and 

 are divided into two families, named Cercariada and Vibrionida. 



The Cercarice found in vegetable infusions have an ovoid or 

 cylindrical body, furnished with a tail, which is not so long as in the 

 Zoosperms ; and in some of the species a mouth, and eye-like specks 

 of a dull red colour have been observed on the anterior part of the 

 body. The family of the Vibrionida, so-named from their darting or 

 quivering motion, includes the eel-like microscopic animalcules which 

 abound in stale paste, vinegar, ic., together with others which are 

 parasitic on living vegetables, where they have excited particular 

 attention, from the damage which they occasion to ears of corn, as 

 the Vibno Tritici, which infests the grains of wheat, and occasions 

 the destructive disease called ear-cockle, or purples. The Vibrio- 

 nidce, as well as the Cercariadce, are said to differ from the true 

 Infusoria not only in the absence of internal stomachs, but also of 

 external cilia, which prevents them from exciting any currents when 

 placed in coloured water. 



On account of the difference in the perfection of structure between 

 the two principal groups of infusory animals, they have been separated 

 and placed iu distinct divisions of the animal kingdom by some 

 naturalists. Professor Owen makes the Polyyattrica the lowest class 

 of the sub-kingdom Acrita, and places the Rotifera in the division 

 Nematimtura. Dr. Grant separates them in the same manner, placing 

 the Polyyattrica in his lowest group Cycloneura, and the Kotifera 

 among the IHpluneura. Ehreiiberg, who retains both forms of 

 Infusoria in one class, subdivides the sections Polygastrica and 

 Rotifera into many minor groups, which are founded upon the modi- 

 fications of different organs : first as to the form of the intestine, 

 whether it is straight or curved, complete or imperfect ; secondly, 

 be considers the varieties of the organs of mastication or dental 

 apparatus; thirdly, many of the Infusoria have the integuments 

 naked ; others are furnished with a crustaceous or horny covering ; 

 but both among the Kotifera and Polygastrica, the naked and coated 

 species are intimately connected together, and very often entirely 

 agree with one another in internal and external structure, with the 

 ingle exception of the consistency of their covering. These characters 

 however, though not separating the animals into distinct divisions, 

 are used as subordinate means of classification : and Ehrenberg has 



formed two parallel series, named Nuda and Loricata ; which corres- 

 pond to certain of the Gymnodes and Crustodes of Bory de St. Vincent. 

 The number of loricated Polygastrica is very small, but among the 

 Rotifera they bear a nearer proportion to the naked species. 



An account of the Rotifera will be found under the article 

 ROTIFERA. We here proceed to give Ehrenberg's classification of the 

 Polygastrica. 



Class Phylozoaria polygastrica. 



Swimming animals, without vertebras, apodal, having sometimes a 

 tail, and very often scattered vibratory or rotatory cilia; : having no 

 heart, but vessels extremely delicate (txSnus), reticulated, transparent, 

 and deprived of proper movement; often rudimentary eyes, with red 

 pigmentum, indicating a nervous system, which however is not 

 apparent ; mouth nude or surrounded by vibratory cilia;, and commu- 

 nicating with several ventricules ; the phalanx apparent, and generally 

 unarmed; no branchia;; organs of generation filiform, reticulated, 

 and granular ; no distinct male organ ; gifted with power of reproduc- 

 tion by spontaneous division. 



Legion 1. Anentera. 

 Mouth communicating with several stomachal vesiculea ; no anus, no 



intestinal tube. 



Order 1. Nuda. Order 2. Loricata. 



Body without envelope. Body enveloped. 



Section 1. Gymnica. 

 Body not ciliated ; mouth with or without cilia; ; no pseudo-pediform 



prolongations. 



1. Gymnica nuda. 1. Gymnica loricata. 



Fam. l.Monadina. Fam. l.Cryptomonadina. 



Form of the body constant, repro- Envelope membranous, sub-globu- 



duction by simple transverse 



division. 



A. Without tail. 

 a. No eyes. 

 * Mouth truncate, terminal and 



turned forwards in swimming. 

 ) Individuals solitary. 



Genus Monas. 

 t+ Individuals solitary when 



lar, and oval. 

 A. Simple, 

 a. No eyes. 

 * Mouth ciliated. 



Genus Cryptomonas. 

 ** Mouth nude. 



Genus Gyget. 

 aa. With a red eye. 



Genus Lagenula. 



young, afterwards aggre- B. Compound, or reproducing by 

 gated and again liberated. internal division. 



Genus Pandorina. 



jfonaa atomot. 



Genus Uvetta. 



H"t Individuals solitary when 



young, dividing crucially. 



Genus Polytonia. 



* Mouth direct, truncate, and 

 turned different ways in the 

 animal's movements. 

 Genus Doxococcui. 

 *** Mouth oblique, without edges, 

 and bilobate. 



Genus Chilomonai. 

 aa. One red eye. 



Genus Microgleaa. 

 B. With a tail. 

 b. Body cylindrical. 



Genus liodo. 

 46. Body angular. 



Genus Urocentrum. 



Fam. 2. Vibrionina. Fam. l.Closterina. 



Body elongate, constant in shape, Envelope round, when rigid, sepa- 

 dividing into many parts, rating spontaneously into two 



mouth terminal (?) or four parts by transverse 



A. Body filiform, cylindrical, divisions, and open at each 



bending itself in undulations. end. 



Genus Vibrio. Genus Closterium. 



D. Body filiform, rigid, and rolling 

 itsolf in spiral. 



