79 CELL CONTENT*. 



Remove the palets from the grain or seed, and mount the sec- 

 tions of the later in glycerin to prevent the disorganization of the 

 compound granules. Observe the reticulated appearance of the 

 latter, due to the lines of union of simple grains of starch; observe 

 the form of the compound granules. (For figures see Goodale's 

 Botany, p. 49, p. 181; Strasburger, pp. 11 and 12.) 



With a little care the coats of the above grains may be sec- 

 tioned for examination at the same time as the starch and compared 

 with those of the wheat. In Fig. 139 (Goodale) the layer (a) is 

 that of the palet, and should not be represented in connection with 

 the true coats of the grain itself. Sections of seeds may be per- 

 manently mounted by removing the water and adding a drop of 

 glycerin jelly. Seal when hard. Strasburger, pp. 11 and 12. 



1. Raphldes needle-shaped. 



Forms of Plant Crystals-; 2. Crystal Prisms prismatic. 



{ 3. SphiEraphldes compound, spherical. 



Illustration Seventh: CRYSTALS. 



Illustration for form 2. The outer dried lamina of an 

 ONION bulb, (Allium Cepa.) 



PREPARATION: Split a thick brown lamina parallel to the sur- 

 face; this may be done by twisting two parts in different directions 

 with the hands. The thin margin of the rent including the cells 

 on the convex surface may be mounted in water. 



OBSERVE: 1. The form of the cells in which the crystals lie. 



2. The various forms of single crystals, viz: Prisms often 

 with modified angles, also hexagons and pyramids if present. 



3. The number of principal faces to the prisms. 



4. The double crystals in the form of an oblique cross; triple 

 crystals if present. Do the axes of such crystals pass through one 

 another? 



TESTS FOR CRYSTALS: 



The greater number of plant-crystals are Calcic Oxalate. 

 A limited number are Calcic Carbonate. 

 Crystals of other salts of lime occur but rarely. 

 Calcic Oxalate is not acted on by Acetic Acid. 

 Calcic Oxalate is dissolved by Hydrochloric Acid without 

 effervescence. 



Calcic Carbonate is dissolved by both acids with effervescence. 

 As the composition of the crystals is uncertain, test with 



