PROCURING OBJECTS. 81 



raphides of oxalate of lime in Rhubarb root, cells with aeieular 

 crystals in Hyacinth, cells with octohedral and prismatic crys- 

 tals in Onion and Squill. Oil-cells in rind of Orange and 

 Lemon, in leaves of Hypericum, and of the Myrtle order. 

 Chlorophyll cells in Mosses, Vallisneria, Chara; cells with 

 coloring matter in leaf of Rottlera tinctoria, and in petals. 



ANIMAL TISSUES, ETC. 



INFUSORIA. These minute animals, some of which are 

 only the 2 smooth P ar ^ f an i Qcn lu diameter, are extremely 

 numerous. Between 700 and 800 different species have 

 been discovered and described. Dr. Ehrenberg, to whom we 

 are indebted for much of our knowledge respecting the ani- 

 malculse, divides them into two classes, i. e., Polygastrica and 

 Rotatoria. The first class is so named from their possessing a 

 digestive apparatus composed of many globular vesicles, which 

 perform the functions of stomachs. The Rotatoria are so 

 called from their possessing rotary organs about their mouth. 

 These are much more highly organized than the others. The 

 Polygastrica increase by self-division, or by the growth of 

 gemmules or buds upon their bodies ; the Rotatoria are herma- 

 phrodite, and oviparous. Many animalculce are loricated; or 

 protected by a shell, or shield, which is generally siliceous : 

 others are destitute of such an appendage. 



The following table exhibits the families or groups into 

 which this interesting department of animal life has been di- 

 vided by Ehrenberg. Those who wish further information re- 

 specting them are referred to his work "Die Infusionsthier- 

 chen," or to Pritchard's "History of Infusoria, Living and 

 Fossil." Dr. Mantell's work on Animalcules contains also 

 much valuable information. 



