THE BRYOPHYTES. 



171 



Where on the thallus are the male branches borne? Meas- 

 ure and state the length of the pedicel, or stalk, in several 

 specimens ; also the diameter of the head, or receptacle. 

 Draw a receptacle seen directly from above, showing the 

 exact number of lobes. Notice grooves on the pedicel. 

 How many are there and where are they situated ? 



Examine plants bearing the female or archegonial 

 branches. Where on the thallus are the female branches 

 borne ? What is the greatest length of pedicel that you 

 find? Do you find grooves on the pedicel? If so, what 

 is their number and where are they situated ? Draw a 

 receptacle seen from above, showing the number of lobes. 

 Also draw plants, showing the male and female inflo- 

 rescence. 



2. With a magnifying glass examine the upper surface 

 of a thallus for rhomboidal areas or areolse. Observe that 

 there is a small opening in the 



center of each areola. This is 

 a stoma, or breathing pore, and 

 is the first instance thus far met 

 of the occurrence of an organ 

 that is common to all the higher 

 plants. Do you find areolae and 

 stomata on the under surface of 

 the thallus ? Among the rhi- 

 zoids find purple and colorless 

 scales. On what parts of the 

 thallus do you find each ? Draw 

 some of the scales and hairs. 



3. Study the structure of the 

 thallus, using first low, then 



high power. Strip off some of the epidermis of the upper 

 surface and examine the areolee, epidermal cells, and 

 stomata. Draw a stoma as seen under high power, 

 showing the number and arrangement of the exterior 



FIG. 99. A female inflores- 

 cence of Marchantia poly- 

 morpha. The archegonia are 

 borne among the hairs on the 

 under surface, which is pre- 

 sented to view in the figure. 

 (After Goehel.) 



