THE VITAL PROPERTIES OF THE CELL 



73 



circulate quite close together, sometimes in the same, sometimes in 

 opposite directions. The 

 nucleus, as well as the 

 chlorophyll and s tarch 

 grains, which lie embedded 

 in the protoplasm, are car- 

 ried slowly along by the 

 current. Similarly in this 

 case the most external hy- 

 aline layer of protoplasm, 

 which is in contact with 

 the cellulose membrane, is, 

 comparatively speaking, at 

 rest. In the second place, 

 the whole body of proto- 

 plasm itself slowly moves 

 along, in consequence of 

 which it changes its form. 

 Broad bands become nar- 

 rowed, and may after a 

 time disappear, delicate 

 threads increase in size, and 

 new processes are formed, 

 just as new pseudopodia 

 are protruded to the ex- 

 terior by Myxomycetes and 

 lihizopoda. Large masses 

 of protoplasm become 

 heaped up here and there 

 upon the layer lining the 

 cell-wall, whilst at other 

 places the coating becomes 

 thinner. 



c. Theories concerning Protoplasmic Movements. 

 Attempts have lately been made by various investigators, Quincke 

 (III. 17), Biitschli (II. 7b), Berthold (III. 2), and others, to com- 

 pare these protoplasmic movements with those exhibited by a 

 mixture of inorganic substances, and thus to explain them. 



Quincke has carefully investigated the movements which occur 

 at the areas of contact of various fluids. He placed in a glass 

 containing water a drop of a mixture of almond oil and chloroform, 



Fig. 41. A B, cells of a staminal hair of Tra- 

 descantia virginica. A Undisturbed streaming 

 movements of protoplasm. B Protoplasm which 

 has run together into ball-like masses in con- 

 sequence of irritation : a cell-wall, b transverse 

 wall of two cells ; c d protoplasm which has 

 massed itself together into small balls. (After 

 Kiihne ; from Verworn, Fig. 13.) 



