CLASS I. 
INFUSORIES (INFUSORIA)." 
THESE animals are called Jnfusories?, because they are to be 
found in infusions of every kind of organic matter, as well vegetable 
as animal. Moreover they live in all stagnant marshy waters, and 
even in running waters, salt and fresh. 
These animals, which on account of their minute size can only 
be discovered, or at all events examined, by means of magnifying 
glasses, were unknown to the ancients. Our LEEUWENHOECK first 
saw them in infusions towards the end of the seventeenth century 
(1675). After LrEEUWENHOECK, many species of these animals 
were observed and described in the last century by Rorse., LEDER- 
MUELLER, VON GLEICHEN and others: but more especially O. F. 
Mvetter, the Danish naturalist, in a work which appeared after 
his death, figured many species, and gave a systematic arrangement 
of the class. In the present century, EHRENBERG has contributed 
most largely to our knowledge of infusories, and since 1828 has 
from time to time published his investigations in the Transactions 
of the Berlin Academy of Sciences, and more recently has collected 
them into a body in a large illustrated work. 
As the diseoveries of astronomers allow us to cast a glance into 
the illimitable extent of space of the universe, so the eye, artificially 
strengthened, affords conviction of the illimitable distribution of 
1 The chief works relating to this class are: 
O. F. Muetier, Animalcula infusoria fluriatilia a marina. Haunie, 1786. 4to. 
The Plates are copied in the Encyclopédie méthodique. 
C. G. EHRENBERG, Die Infusionsthierchen, als vollkommene Organismen. Nebst einem 
Atlas von 64 colorirten Kupfertafeln, Leipzig, 1838 folio. (G. VALENTIN gave in his ° 
Repertorium fiir Anat. und Physiol. tv. Bd. Jahrgang, 1839, a detailed abstract of 
this work, containing the characters of all the genera and species. s. 136—18r.) 
Histoire naturelle des Zoophytes. Infusoires, comprenant la Physiologie et la Classifi- 
cation de ces Animaux, par F, DusaRDIN, Paris, 1841. 8vo. 
Die Infusionsthiere auf ihre Entwickelungsgeschichte untersucht von DR FRIEDRICH 
SrErn, mit 6 Kupfertafeln. Leipzig, 1854. 4to. 
2 First by LEDERMUELLER, according to EHRENBERG, 
