INFUSORIAL ANIMALCULES. 21 



side by side, as in the Triophthalmus ; and at others, 

 arranged triangularly, as in the Eosphora. In the Cyclo- 

 glena, they form a circle ; and, in the Theorus, a cluster 

 on each side. 



Section IV. — Distinction between the Infusoria and other 

 Minute Animals, ^'c. 



In our present state of knowledge, with respect to 

 organic bodies, there are many difficulties in the way of 

 determining on such boundaries as may reduce them to 

 well defined groups. Even the line of demarcation between 

 animals and plants, which, at the first blush, might be 

 supposed to be so very broad and distinct, upon a more 

 minute consideration, is not easily settled. The plan of 

 this work will comprehend a description of those creatures 

 which are generally to be found in animal or vegetable 

 infusions, and such as agree with them in their general 

 structure and habits. 



In Die Infusionsthierschen, the author has occasionally 

 introduced animals which have been classed under other 

 divisions of the animal kingdom. As examples, we may 

 take the family Dinobryonia, the members of which are 

 classed as zoophites by other naturalists. Again, in the 

 genus Bodo, some of the species are proper Entozoa, 

 and, therefore, ought to be excluded. Having, however, 

 taken that work as the basis of my arrangement, all the 

 species described therein will be found here. 



With regard to the spermatozoa of animals, our knowledge 

 of them is but scanty and confused, arising principally 



