THE PTERIDOPHYTES 283 
863. Asexual Reproduction, Spore-Cases and Spores.!— Pick out 
some spore-cases from a sorus (Fig. 204, C, D), mount them in water, 
examine with l.p., and note: 
(a) The stalk. 
(0) The spore-cases proper. Draw. 
(c) The partial ring of thick-walled cells enclosing the spore-case. 
(d) The spores. These should also be examined with h.p. Draw. 
The spores are scat- 
tered by the splitting 
open of the spore-case 
when very dry, pulled 
apart by the elastic ring 
(Fig. 204, D). 
364. The Gameto- 
phyte (Prothallium) and 
Sexual Reproduction. — 
Material for this study 
may be obtained by 
dusting spores of any 
desired species of fern 
over bits of brick or 
broken flower-pots or 
earth kept moist under 
a bell-glass. The spores 
of most genera are long- 
= haan lina - Fig. 205. Prothallium of a Fern (Polystichum). 
madly ateny Sueouhs View of the under surface. 
after they mature. They 
should be sown six 9%: growing point; ar, archegonia; an, anther- 
: idia; 7h, rhizoids; s, region in which the spore 
weeks or more before germinated. (x about 8.) 
the material is needed 
for class use. Germinating spores in all stages of development may 
also be found on flower-pots containing greenhouse species of fern, 
particularly Adiantum. Mount some of the material, examine with 
h.p., and note : 
(a) Several stages in the germination of spores. Draw. 
1 Polypodium is excellent material for the study of the sporangia. ‘ The 
minute structure of the vegetative portion of the fern is here omitted. 
