98 MORPHOLOGY AND LIFE HISTORY 



thread-like network. Does starch occur in this 

 tissue? Some of the cells unite, end to end, form- 

 ing tubes to conduct liquids. 



6. Between the cells of both cortex and medulla is a 

 mucilaginous layer, formed by the swelling and 

 chemical transformation of the middle lamella, 

 or layer that separates adjacent cell-walls. 



7. Make a drawing showing the differentiation of 

 tissues from the surface to the center of the thallus. 



8. Sterile Conceptacles: Secure sections passing through 

 one or more of the ostioles that do not occur on the 

 receptacles. These ostioles will be found to open 

 into spherical or pear-shaped cavities (conceptacles) 

 imbedded in the cortical tissue. In viewing a cut 

 end of the thallus with the naked eye, these cavities 

 appear as minute dots underneath the epidermoidal 

 layer. 



9. Observe in these conceptacles, under the low power, 

 numerous long hairs (paraphyses). Of how many 

 cells is each composed? Do they extend through 

 the ostioles to the surface? With what are they 

 connected? 



E. Physiology: 



1. Of what advantage to an aquatic plant may the 

 air-containing bladders be? 



2. Does the plant grow attached to a substratum? 

 If so, how? 



3. How do you think the plant takes in its food ele- 

 ments? 



4. Ascertain if the plant has chlorophyll. Is photo- 

 synthesis possible? 



5. Would it be an advantage to this plant to have a 

 system for conducting liquid nutrients from one 

 place to another? Is such a system present? 



