280 STRUCTURAL BOTANY 



advancing edge of the mass (a, a in Fig. 109) is con- 

 stantly putting out feelers (pseudopodia, as they are 

 called), which are sometimes withdrawn again, but more 

 often maintain their position, and are increased by the 

 flow of protoplasm from behind. The outer layer of the 

 whole plasmodiuni is clear and transparent; the inner 

 mass is very granular, and the granules are especially 

 abundant in the veins. Many of the granules consist of 

 lime (calcium carbonate), and it is around these lime- 



FfG. 109. Badhamia utricularis ; plasmodium, from a stained 

 specimen, prepared by Mr. A. Lister, a, a, advancing 

 margin. Magnified about 5. (R. S.) 



granules that the yellow colouring-matter is chiefly 

 deposited. The clear part of the protoplasm is colour- 

 less. When a pseudopodium is first extended it consists 

 of the clear part (hyaloplasm) only; subsequently the inner 

 granular substance flows into it and increases its mass. 



The internal movement along the veins is extremely 

 active, and can be followed with ease under the microscope 

 by means of the granules which are swept along with 

 the current. The flow is curiously rhythmical. In 

 each vein the current sets steadily in one direction for 



