G 



BOTANY. 



masses in the large vacuole ; these again may produce vacuoles within 

 themselves, and thus give rise to a peculiar and at first sight perplex- 

 ing structure (Fig. 4). 



6. The most remarkable peculiarity of living protoplasm is 

 its physical activity. "When the proper conditions are pres- 

 ent, a living mass of protoplasm is apparently never at rest, 



but, on the contrary, 

 continually altering its 

 shape and changing the 

 position of its constit- 

 uent parts. The move- 

 ments are all of the 

 same general nature ; 

 each one may be regard- 

 ed as the aggregate re- 

 sult of the chemical and 

 physical changes taking 

 place in the substance 

 of the protoplasm. 



We may study the ac- 

 tivity of protoplasm 

 under two conditions, 

 which will give us the 

 two cases. (1.) The 

 Activity of Naked Pro- 

 toplasm, and (2.) The 

 Activity of Protoplasm 

 enclosed in a Cell-wall. 

 7. The Activity of 

 Naked Protoplasm . 

 The low organisms 

 known as the Myxomy- 

 cetes, or Slime Moulds, 

 present the best examples of the activity of naked vegetable 

 protoplasm. In their plasmodia (as the masses of naked proto- 

 plasm are called), many kinds of movements may be observed, 

 the commonest of which is streaming. In plasmodia com- 

 posed of thin (i.e., watery) protoplasm, streams or currents 

 of the latter may be seen running in various directions 



Fig. 4. Forms of the protoplasm contained in 

 cells. A and B, of Indian Corn (Zea maix) ; A, 

 cells from the first leaf-sheat'.i of a germinating 

 plant, showing the frothy condition of the proto- 

 plasm, the many vacuoles separated by thin 

 plates. B, cells from the first internode of the 

 germinating pl>nt; the protoplasm is broken up 

 into many rounded masses, in each of which there 

 is a vacuole, 6 ; these are the so-called " sap- vesi- 

 cles." C, a cell from the tuber of the Jerusalem 

 Artichoke (Helianthus tuberosvs) after the action of 

 iodine and dilute sulphuric acid ; h, cell-wall ; fc, 

 nucleus ; p, contracted protoplasm. After Sachs. 



