48C 



LIFE-HISTORIES 



Fig. 316. — Sea-tangles (Laminaria spp., Sea-tangle Family, Laminariacece) . 

 Various forms more or less reduced in size; the larger ones often having 

 the stalk over 1 m. long and the expanded part 2 m. (Luerssen.) — 

 These brown, leathery seaweeds are familiar objects along our coasts. 



leaf joins the stalk there is a cell-mass which retains this 

 power, and from time to time exhibits it in a striking waj^; 

 that is to say, it forms a new pseudo-leaf at the base of the 

 old one which it eventually casts off, as indicated in the figure. 

 Any mass of connected cells all of which are similar in origin 

 and character is called a tissue. An undifferentiated tissue, 



