VEGETABLE HISTOLOGY AND PHYSIOLOGY. 



147 



uniform in shape and size 

 and somewhat lens-shaped. 



375. Crystals of a great 

 variety of shape are found 

 in some of the cells of 

 most plants of the higher 

 orders ; the most simple of 

 these forms are cubical or 

 prismatic ; but they occur 

 in almost every variety of 

 polyhedral form. In some 

 orders they appear in slen- 

 der needle-shaped bodies 

 called Raphides. They usu- 

 ally occur, solitary or in 

 masses, in the cell cavity, 

 but are not unfrequently 

 found in the cell -wall 

 (Figs. 474, 475). 



Plant 



473, A, is a cell from the endosperm of a graia'of 

 Indian Corn, crowded with starch-grains ; the grains 

 i -i marked a, 6, c, etc., to g are also from the interior of 



LiltJ a g ra i n o f corn. The grains marked B are from the 



residua of the materials 



used in the chemical combinations that have taken 



place in the cell under the 

 action of sunlight, and are 

 usually composed of lime 

 carbonate or lime oxalate. 

 Other calcic combinations 

 are, however, frequently 

 present. The difficulties at- 

 tending the separating of 

 plant crystals from their 

 474, A, Beet ceiis with R surroundings have thus far 



stellate masses of crystals ; B, R, inner cells, with -j -j i m<-i-IV1 /- !--* 



raphides escaping ; C, aleurone crystal. Tendered it impOSSlble 1H 



