CRYPTOGAMS 



1654 



CRYSTALLIZATION 



CRYPTOGAMS, krip' toh gamz, or FLOWER- 

 LESS PLANTS, is a term which includes all 

 plants which do not bear seeds. The name is 

 derived from Greek words meaning hidden mar- 

 riage, or "reproduction that is difficult to see." 

 Among the cryptogams are the ferns, the 

 mosses and the algae and fungi. The name is 

 really applied in error, due to the fact that 

 it was at one time believed that stamens and 

 pistils were the only sex organs and so the re- 

 production of flowerless plants seemed obscure. 

 The sex reproduction of cryptogams by spores 

 is really more clear than that of phanerogams 

 by seed. See BOTANY ; PHANEROGAMS ; SPORE. 



CRYSTALLINE, kris ' t al in, ROCKS . Gran- 

 ite and marble, especially when polished, show 

 that they contain a great number of crystals 

 cemented together. Rocks having this struc- 



By these experiments and the examination 

 of the substances with a magnifying glass, 

 we learn that many solid substances are formed 

 by masses of crystals crowded together. This 

 method of formation is called crystallization. 



Systems of Crystals. Notwithstanding the 

 large number of crystals, they are all system- 

 atically arranged and are classified under six 

 systems, all of which are based upon the cube 

 and its modifications. To illustrate, the cube 

 has six sides or faces. If we cut four of its 

 edges we have increased the number of faces 

 to ten; if we cut all the edges we increase the 

 number to eighteen. Now if we cut the corners 

 we have a solid with twenty-four surfaces. The 

 systems of classification are as follows: 



The Regular Cubic System. The perfect 

 crystals of this system are cubes. Common 



FIG. 2 



FIG. 3 



ture are called crystalline rocks. Some varie- 

 ties of quartz, limestone and hornblende are 

 masses of crystals and make very beautiful 

 cabinet specimens. Most crystalline rocks once 

 existed in a molten state and crystallized as 

 they cooled. See IGNEOUS ROCKS. 



CRYSTALLIZATION , kris taliza' shun. Let 

 us make some rock candy. We will dissolve 

 granulated sugar in hot water until we have 

 a syrup. We will then stretch one or more 

 strings across the vessel in the syrup and set 

 it away to cool. In a few hours clusters of 

 crystals will be formed about the strings, 

 and these crystals make our rock candy. Let 

 us examine them. How many sides have they? 

 Are all the sides the same size? Do all the crys- 

 tals have the same number of sides? Get some 

 rock salt and compare it with the crystals of 

 sugar. How do they differ? Dissolve as much 

 alum as you can in hot water. Stretch strings 

 through the solution and let it cool. How 

 do the crystals- of alum differ from those of 

 the sugar and the salt? 



FIG. 4 



salt, iron pyrite, galena, lead ore, silver, copper 

 and gold are all illustrations of this system 

 (Fig. 1). By cutting the cube as shown in b 

 a double pyramid with equal faces is formed. 

 By cutting the edges as shown in c we have 

 a crystal with twelve equal sides. Alum and 

 the garnet are good illustrations. 



FIG. 5 



FIG. c 



The Square Prismatic System. The rec- 

 tangular prism forms the basis of this sys- 

 tem (Fig. 2). This gives the prism and the 



