Cells and Cell Principle 41 



ANIMAL CELLS 



PLANT CELLS 



3. Protoplasmic Strands ("Bridges"). 

 — In both plant and animal cells 

 there may be fine protoplasmic 

 strands extending from one cell to 

 another to assist in the continuity 

 between adjacent cells (Figs. 10 

 and 175). 



3. Protoplasmic Strands ("Bridges"). — 

 The walls of certain plant cells are 

 not uniformly solid but contain mi- 

 nute, thin areas called pits which 

 permit the passage of water and dis- 

 solved materials between adjacent 

 cells. In other cell walls, numerous 

 small canals contain very delicate 

 protoplasmic strands called plasmo- 

 desmata (plaz mo -dez' ma ta) (Or. 

 desma, bond) for the exchange of 

 foods, the coordination of adjacent 

 cells by the transmission of stimuli, 

 etc. (Fig. 10). 



4. Centrosome or Central Body. — Just 

 outside the nucleus there often is 

 centrosome consisting of a small, 

 granular, deeply stained centriole 

 (frequently two) surrounded by a 

 denser area of cytoplasm, the faintly 

 stained centrosphere. This body 

 takes part in cell division and is not 

 present in all animal cells and is 

 not present in higher plant cells. 



4. Centrosome or Central Body. — This 

 small body near the nucleus of cells 

 of certain lower plants (algae, fungi, 

 etc.) is absent in higher plant cells. 

 When present, it is associated with 

 cell division. 



5. Mitochondria or Chondriosomes (mi 

 to -kon' dria) (Or. mitos, thread; 

 chondr OS, granular) (kon' dre o som) 

 (Or. chondros, granular; soma, 

 body). — These cytoplasmic bodies 

 occur in most cells and appear as 

 granules, rods, filaments, and some- 

 times as networks, of variable shapes 

 and sizes. They are common in 

 young cells and are thought to be 

 forerunners of other structures in 

 adults cells. It has been suggested 

 that they may assist in cell respira- 

 tion. 



5. Mitochondria or Chondriosomes. — 

 These small, granular or rod-shaped 

 structures are commonly present in 

 plant cells, being visible when prop- 

 erly stained. It is thought that 

 they may have the following func- 

 tions: centers of protein formation 

 and digestion; assist in cell division; 

 form and develop certain plastids. 



Golgi Apparatus or Golgi Bodies 

 (gol'je) (after Golgi, Italian scien- 

 tist). — This is frequently a netlike 

 structure at one side of the nucleus, 

 although in certain cells it may be 

 diffused. It often surrounds the 

 centrosome. It is thought to have 

 a secretory function, or to assist in 

 the metabolism of certain foods. 



Golgi Apparatus or Golgi Bodies. — 

 It is not certain, in the light of pres- 

 ent investigations, whether struc- 

 tures comparable to Golgi bodies of 

 animal cells are present in plant 

 cells. 



