110 REPRESENTATIVE PLANTS 



may be seen in large fish and sea-food stores, having been 

 shipped as packing for lobsters, crabs, and other sea foods. 



General appearance. Examine the specimens furnished 

 and observe the peculiar feeling and consistency of the whole 

 plant. Of what does the consistency remind you? The 

 plants grow at tide level, where wave action is very strong. 

 How does the general nature of the plant fit it for such a 

 place of growth ? Observe enlargements here and thereon 

 the main axis. Cut one open. What is it ? What can be 

 its purpose? These structures are bladders. What is the 

 color of the plants? How does it vary from end to end? 

 Being an alga, it must contain chlorophyll. How do you 

 exi)lain the color observed ? 



Branching and main axis. Examine the branching. What 

 do you observe on drawing a plan, showing all the branches, 

 properly proportioned? Such a method of branching 

 is called dichotomous. Examine the main axis, and 

 observe whether a holdfast at the large end as present or 

 not. The axis may or may not have a central line or ridge, 

 the midrib, and a lateral expansion, ivings, according to the 

 kind studied. 



Branchlets and conceptacles. Examine the final divisions 

 of the axis, which in ascophyllum, in particular, feel like 

 the bladders. Cut one open. Is it hollow? These struc- 

 tures may be called branchlets. Examine attentively and 

 observe the minute brown spots or dots scattered over their 

 surface, or collected numerously in some branchlets. These 

 are concex)tacles and contain the reproductive gametes. In 

 fucus the fertile branchlets (bearing conceptacles) are quite 

 distinct, and commonly in pairs. 



Reproduction. Examine {Ip) or {lip) prepared conceptacles, 

 and observe the anfheridia and oogonia. Their full explan- 

 ation may properly be left to the instructor as special 

 preparations are required in order to see all the reproductive 

 structures plainly. 



