VII 



THE HISTOLOGY OF THE CELL 



FIG. 113. A, cell from the endosperm of the Castor 

 Oil plant ; B, aleurone grains ; g, glcboid ; k, 

 crystalloid. (.X 540.) (S.) 



globoid is formed of a double phosphate of lime and magnesia. 



If a section of a Castor Oil seed be made and examined by the 



high power of the 



microscope, the 



aleurone grains 



will be seen to be 



embedded in the 



protoplasm, which 



is also rich in oil. 



The proteids are 



stored up in plants 



principally in the 



form of aleurone 



grains. They are 



large in oily seeds 



but small in starchy 



seeds. 



The crystalloids 

 are sometimes 

 found free. The 

 crystalloids differ 

 from mineral crys- 

 tals because they 

 swell up if treated 

 with various re- 

 agents. 



Fats. Drops of 

 oil are found in the 

 protoplasm in the 

 cells of many 

 plants. These 

 drops are very nu- 

 merous in the case 

 of the seeds of the 

 Castor Oil plant, 



Rape, Flax, and in the fruit of the Olive. The non- nitrogenous 

 substances stored up as reserve material in the above plants 

 occur as drops of oil. When the seeds germinate the fat is 

 converted into sugar. 



Raphides. In most plants crystals of calcium oxalate are 



FIG. 114. Section of grain of Wheat. /, pericarp ; /, 

 seed coat ; al, aleurone grains ; am, starch grains ; 

 n, cell nucleus. 



