286 



STRUCTURAL BOTANY 



its struggles dragging it in until it is enclosed in a 

 vacuole of the protoplasm, and ultimately digested 

 (Fig. 113,4 



The swarm - spores multiply repeatedly by division 

 into two, the movement ceasing before the division 

 takes place, and starting again when the daughter-cells 

 are formed. The division of the nucleus precedes that 



of the cell. The swarm- 

 spore may also become 

 encysted, surrounding 

 itself with a cell -wall, 

 from which it afterwards 

 escapes, resuming its 

 active career. The en- 

 cysted swarm -cells bear 

 the name of microcysts. 



From the swarm-spores 

 the plasmodium is built 



FIG. 114. Didymium difforme ; young *- , 



plasmodium with attendant swarm- Up. Beiore this happens 



cells, m microcyst. One microcyst th withdraw their cilia, 

 is being digested in a vacuole (i>). * 



s, empty spore-membrane. Magni- and henceforth confine 



themselves to creeping 

 amoeboid movements. 

 When two creeping myxamoebce (as they are called at 

 this stage) meet, their protoplasm flows together into 

 a single mass. Then others join them, and enter into 

 fusion, and so the beginning of a new plasmodium is 

 made. More and more swarm-cells are attracted to the 

 spot, and join on to the fused mass (as shown in Fig. 

 114) until a large number have united. The cells com- 

 pletely fuse, but their nuclei remain distinct. 



Thus we see that a plasmodium is a compound 

 structure, built up in the first instance by the union of 



