THE PTEBIDOPHYTES. 



197 



9. Examine the spores. What is their shape ? What 

 is the character of their covering ? Crush some of the 

 spores by pressure 011 the cover glass. Treat with 

 Schultze'e solution. Of what is the covering or exospore 

 composed ? Treat another mount of crushed spores with 

 iodine solution. Do they contain starch ? Do you find a 

 nucleus ? 



10. Study the protonemse. These are easily cultivated 

 as follows : Sow the Fern spores on a fresh moist sod 

 placed in the bottom of a glass 

 jar ; also on the moist sides of the 

 jar, and on a sheet of glass to be 

 used as a cover to the jar. As 

 Fern spores usually require a 

 period of rest before they will 

 germinate, use spores of the pre- 

 vious year. Keep this moist 

 chamber under suitable condi- 

 tions of heat and moisture, but 

 not in too strong sunlight. The 

 spores will begin to germinate in 

 about a week, and the progress 

 of the growth may be watched 

 by making examinations at inter- 

 vals of a few days. Draw speci- 

 mens showing successive stages 

 of development. Notice that the growth begins by the 

 bursting of the spore covering. Notice that a rhizoid be- 

 gins to form simultaneously with the first division of the 

 spore contents, and that other rhizoids are formed later. 

 Do the cells of the protonema contain nuclei? Do they 

 contain chromatophores ? Starch ? Find protonemsB that 

 show at the distal end a triangular apical cell resembling 

 the apical cell of the apical bud ; it may not be easy to do 

 this. Notice that the cells of the protonema are at first 



FIG. 123. A sporangium of 

 Pteris serrulata. s, a 

 spore ; c, capsule ; a, an- 

 nulus ; p, pedicel. (After 

 Sumiuski.) 



