40 



PRELIMINARY STUDIES. 



FIG. 17. 1, Upper part of a female Moss 

 plant, showing club-shaped archegonia 

 concealed among the leaves; 2, an an- 

 theridium, such as are borne in the rose- 

 shaped cluster of leaves at the top of the 

 male plants, allowing the antheroids to 

 escape. Each of the cells at a contains 

 an antherozoid in a gelatinous covering. 

 (Thome'.) 



under high power. The 

 ripened spores are scat- 

 tered over the ground, 

 and there develop into 

 simple aggregations of 

 cells, called protonemce. 

 These resemble the pro- 

 tonemse of Ferns, but 

 differ from them essen- 

 tially in their further 

 growth, which is by 

 sending off buds or side 

 branches. These buds 

 develop into the ordi- 

 nary Moss plant. 



5. Certain plants of 

 Polytrichum are ster- 

 ile. In early spring 

 these may be mistaken 

 for the female plants, 

 but later the male, fe- 

 male, and sterile plants 

 are easily distinguished. 

 (See Fig. 16.) 



The Pond Scums. 



Collect from stagnant pools some of the slimy green 

 growth commonly known as Frog Spittle. Examine under 

 both low and high powers of the compound microscope. 

 Different varieties may be found. It will be sufficient for 

 the present purposes if any variety in the conjugating con- 

 dition is obtained, as these plants are to be studied more 

 minutely later. Material in the conjugating condition 

 that has been preserved in formalin or alcohol may be 



