132 THE SCIENCE OF LIFE. 



and near these a narrow slit, which, on being enlarged, 

 will show the simple flower, like a membraneous bag, 

 and containing two stamens and one ovary, with its style 

 and simple stigma. 



IT. Protophytes, Thallogens, and Acrogens have been 

 classed together in the artificial system of Linnaeus as 

 Cryptogamia, (from cryptus, hidden, and gamos, nuptials,) 

 in allusion to the inconspicuous character of their repro- 

 ductive organs ; while Endogens and Exogens are called 

 PJianerogamia, (phaneros, visible, and gamos, nuptials,) 

 since they have perceptible reproductive organs formed 

 of stamens and pistils. To these essential parts we fre- 

 quently find two envelopes added, the calyx and corolla. 

 These parts make up the flower, and the Phanerogamia 

 are not infrequently known as flowering plants. 



The flower consists of whorled leaves placed on an 

 axis, the internodes of which are not developed. There 

 are usually four of these whorls. The outer whorl is the 

 calyx, the next the corolla, the third the stamens, and 

 the innermost the pistil. In Exogens the calyx is usu- 

 ally green and the corolla colored, but in Endogens both 

 frequently display rich coloring, and are apt to be con- 

 founded, so that the term perianth is usually applied to 

 the flowers of Endogens, whether colored or otherwise, 

 (peri, around ; anthos, flower.) 



The parts of the calyx, when separate, are called se- 

 pals, and the leaves of the corolla petals. Stamens have 

 two parts, the filament, or stalk, and the anther, or 

 broader portion, corresponding to the folded blade of 

 the leaf, and containing fertilizing grains called pollen. 

 The pistil is also made up of two parts, the ovary, con- 



