486 LIFE-HISTORIES 
ip eat 
MET 
Fic. 316.—Sea-tangles (Laminaria spp., Sea-tangle Family, Laminariacee). 
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. 
de (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 way; 
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, 
