388 AFFEArorx. 



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 fiowers. Observe the broad short stalk ; the thin 

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

 Tear open these and observe the innumerable small spores, 

 microspores (or pollen grains). 



7. Deuionsiration. Mount mature microspores in water and show 

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

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

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

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

 sperjnary , simple by reduction. {T[ 385.) 



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

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

 so-called bracts ; (b) thick fieshy 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 

 integiiuient and a sporangium containing a single megaspore. 

 Note the opening in the integument (w/^-ri'/'rA') 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 e.xcessive 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. (1^ 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 sforanp;itim surrounded by the iiiU-giimcnt prolonged 

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

 interior of the megaspore, now partly filled with the voting feniale 

 gametophyte. (Compare fig. 319.) 



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

 compound microscope, especially (") the female gametophyte, 

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



