REVIEW ON CELL -CONTENTS 251 



in October. To study crystals and cystoliths : section the 

 rootstock of skunk cabbage or Jack-in-the-pulpit, the leaf 

 of Ficns elastica, the leaf of ivy (Hedera helix) ; make a 

 separate mount of each in water, and examine with the 

 high power. When the crystals are found, draw them, 

 with a view of the adjacent cells. Make a similar study 

 of a bit of tliin onion skin. 



405. Summary of cell-contents and products: 



1. Chlorophyll. 



2. Cell-sap, and substances found in solution. 



3. Starch. 



4. Amylo-dextrine. 



5. Alenrone grains (crystaloids and globoids). 



6. True crystals, and other mineral matter. 



Review. — Name six classes of contents or products of the cell. 

 Where found ? Of what use? What is chlorophyll ? What is its 

 use? What is assimilation (170)? Give outline of the products of cells 

 found dissolved in cell-sap. What are the uses of sugar to plants? 

 Name some kinds of sugar found in plants. Describe an experiment 

 to test for glucose. Same for cane sugar. How may we find the oil 

 in plants? Describe an experiment for the study of gum-resin. Why 

 does the juice containing it appear white? Describe starch grains of 

 potato. Tell how starch grains of other plants studied differ from 

 those of potato. What are the uses of starch to the plant ? Where 

 is the plant's starch factory? Describe an experiment to test for 

 starch. Name some plants in which we may find amylo-dextrine. 

 How does its test differ from that for starch ? What are aleurone 

 grains? In what cells are they found in kernels of wheat? Name 

 some of the forms in which we find true crystals in plant cells. 



Note to Paragraph 397. — The digestion of starch is produced 

 by means of enzyms or unorganized ferments (i. e., ferments which 

 are not bacterial or fungal, but are chemical substances). These 

 ferments, as diastase, are present in seeds and other living tissues 

 containing starch. During dormant periods the enzyms either are 

 not present, or their action is prohibited by the presence of other 

 substances. There are various specific enzyms, each producing 

 definite chemical changes. 



Grape sugar and its associate, fruit sugar, appear to be the forms 

 most generally useful to plants. Cane sugar is readily inverted into 

 these sufirars 



