THE LIVING SUBSTANCE OF PLANTS. 1*] 



56. Protoplasm occurs in the living parts of all plants, 



The substance we have found in the alga spirogyra, in the root 

 hairs of the corn seedling, in the threads of the black mould, is 

 essentially alike in all. It may be arranged differently in the 

 different plants, but its general appearance is the same. It 

 moves quite rapidly in the cells of some plants, but so slowly 

 in others that we may not see the movement. Yet when we 

 treat the protoplasm with well-known reagents the reaction in 

 general is the same. It has been found by the experience of 

 different investigators that the substance in plants which shows 

 these reactions under given conditions is protoplasm. We 

 have demonstrated to our satisfaction then that we have seen 

 protoplasm in the simple alga spirogyra, in the root hairs of the 

 seedling, and in the threads of the black mould. If we chose 

 to make sections of the stems and leaves of the seedling, or of 

 the living parts of other higher plants, we should find that 

 protoplasm is present in all these living cells. We then con- 

 clude that protoplasm occurs in the living parts of all plants. 



57. Summary of observations on protoplasm. While we 

 have by no means exhausted the study of protoplasm, we can, 

 from this study, draw certain conclusions as to its occurrence 

 and appearance in plants. Protoplasm is found in the living 

 and growing parts of all plants. It is a semi-fluid, or slimy, 

 granular, substance; in some plants, or parts of plants, the 

 protoplasm exhibits a streaming or gliding movement of the 

 granules. It is irritable. In the living condition it resists 

 more or less for some time the absorption of certain coloring 

 substances. The water may be withdrawn by glycerine. The 

 protoplasm may be killed by alcohol. When treated with 

 iodine it acquires a yellowish-brown color. 



Material. Freshly formed mycelium of the common black mould (see 

 demonstration 8, which also see for culture material and vessels). 



A solution of iodine. A \% aqueous solution of eosin. 95$ alcohol. 



Watch glasses to receive small quantities of the solutions when the pupils 

 are engaged in exercise 12. 



Microscope, etc. 



