388 APPENDIX. 



that of the dwarf shoots on the upper part of the same axis. 

 What is a flower? (p. 236.) 



6. Dissect off a single micro-sporophyll (stamen) from one of 

 the staminate flowers. Observe the broad short stalk ; the thin 

 upturned end ; the two large sacs, sporangia, on the under side. 

 Tear open these and observe the innumerable small spores, 

 microspores (or pollen grains). 



7. Demonstration. Mount mature microspores in water and show 



(a) the spore itself (the central body) with two bladdery enlarge- 

 ments of the outer wall to secure buoyancy in air ; (b) the immature 

 male gametophyte inside, consisting of two cells, the smaller rep- 

 resenting the vegetative part (a mere rudiment) and the larger the 

 spermary, simple by reduction. (H 385.) 



8. Examine a pistillate flower. Observe that it shows from the 

 surface two kinds of leaves : (a) thin ones with toothed edge, the 

 so-called bracts ; (b) thick fleshy ones with a prominent point, the 

 carpels. These are probably two parts of one structure, the 

 sporophyll, which is deeply divided ; but there is wide difference of 

 opinion as to the exact nature of the bracts and carpels. 



9. Dissect out a carpel and observe (a) the broad attachment ; 



(b) the ridge on the upper side (keel) extending into a prominent 

 point ; (c) the two enlargements on the upper side near the base, 

 the ovules, and their oblique position. The ovules consist of an 

 integument and a sporangium containing a single megaspore. 

 Note the opening in the integument (micropyle) at the end nearest 

 the base of the carpel, with two prolongations right and left. 

 (Fig. 246.) 



10. Examine a year-old cone. Observe the excessive growth 

 of the carpels as compared with the bracts. Can you find the 

 latter by cutting the cone smoothly lengthwise through the cen- 

 ter ? Note the woody texture of all parts. (IT 404, fig. 341.) 



11. Dissect out an entire carpel. Observe the obliquely placed 

 ovules (Fig. 342). 



12. Cut a thin longitudinal section of the ovules and the carpel. 

 Observe the sporangium surrounded by the integument prolonged 

 beyond it at the orifice ; inside the sporangium a cavity, the 

 interior of the megaspore, now partly filled with the young fern ale 

 gametophyte. (Compare fig. 319.) 



13. Demonstration. In a similar section show these parts under 

 compound microscope, especially (a) the female gametophyte, 

 growing inside the spore which has not escaped from the sporan- 



