LIVING MATTEK 



15 



cell, so, on the other hand, a number of cells fusing their protoplasm 

 into a single mass may 

 compose a single multi- 

 nuclear cellular in- 

 dividual (Fig. 4). Multi- 

 nuclear cells are fairly 

 common, whether as a 

 living species or as the 

 complex elements of 

 higher organisms. They 

 represent transitional 

 forms between the 

 simple niononuclear cell 

 and a tissue, which is 

 an aggregate of similar 

 but individually dis- 

 tinct cells. In some of 

 the lower creatures, 

 known as Myxomycetes, 

 the multinuclear proto- 

 plasmic mass assumes 

 externally the aspect of 



FIG. 3. 



Stentor Roesdii. (Verworn.) 1, Complete in- 

 dividual, trumpet -shaped, showing in the body -axis a 

 very elongated nucleus of lighter appearance. When 

 bisected at A, each segment regenerates into a smaller, 

 complete individual, the upper half being represented by 

 2, the lower by 3. 



a network which may 



cover an area of several 



decimetres (plasmo- 



dium). This reproduces 



by spores, and from each spore there develops an amoeboid cell of 



distinct outlines. Eventually 

 the outlines of the cells dis- 

 appear, and they resume the 

 form of a reticulated plasmo- 

 dium (Strasburger). This 

 fusion of many cells into a 

 simple multinuclear proto- 

 plasmic mass is termed a 

 syncytium (Fig. 5). 



The external form of the 

 cell may vary greatly both 

 in organisms which consist of 

 a single morphological ele- 

 ment, and in multicellular 

 organisms. A primary dis- 

 tinction must be made be- 



Fio. 4. Kvdorina degans. (Verworn.) Complex f WPPT1 ppll- n f variahlp flnrl 



individual (colony) resulting from fusion of a SWeen C VRriaDlC, ana 



number of flagellated individuals into a common those of fixed form. The 



globular mass of gelatinous substance. , . , 



former are termed amoeboid, 

 because they change their shape like the Amoebae (Fig. 1), which 



