I 



8 Pkactical Exekcises. 



20. — Detach with tlie point of a pencil the pollen-masses in any orchid flower, thus imitating the action 

 of an insect. Note the downward contraction of the pollen-mass shortly after its withdrawal. 

 "What purpose is served by this contraction ? Extract also the pollen-masses from a flowei' of 

 Milkweed. 



21. — Observe whether insects visit the flowers of anj' of the following- : Pine, Willow, Cucumber, 

 Maple. 



22. — Make and draw sections of six different ovaries. 



23. — Soak a bean in water for an hour or two, and then dissect it, exhibiting all its parts. 



24. — Compare the pappus of the Dandelion with the silky hairs u)jon the seeds of ]\Iilkweed and of 

 Willow-herb. Note differences of origin. 



25. — Bury a bean and an acorn in moist, warm sawdust, and note any difference in the phenomena of 

 germination. 



2^. — Gather a few acorns and seeds of the Red Maple and lay them awa\' for tlie winter. In the 

 spring test their germinating powers. 



27. — Examine scales of green pine-cones, and also of ripe ones. 



28. — .Study the dehiscence of the ovary in Purslane, Shepherd's Purse, Catchfl} , Columbine, Mallow, 

 Morning Glory. 



29. — Dissect out the embryos from six albuminous seeds. 



30. — Observe tlirough a good microscope, and make drawings of : — 



(a) Six different ])ollen-grains. 



(b) A thin slice of Elder pith. 



(cj A shred torn from the under surface of a leaf. 

 (dj A similar shred from the vipj^er surface. 



(e) A cross-section of a bit of Lilac leaf with a vein in it. 



(f) A plant-hair. 



(g) A vertical section through the tip of a I'ootlet. 

 (h) A thin slice of Potato. 



(i) The bloom on a Cabbage-leaf. 



31. — Make cross-sections of the Bamboo and a branch or small stem of anj- of our native woods. 

 Examine with a lens, and write notes on the different appearances presented. 



32. — Examine the bark of a 3'oung tree and also of an old one of the same kind. Note any differences 

 and account for them. 



33. — Examine a bit of the under side of a leaf of Sweet-brier under a good microscope. Give your 

 opinion of the source of its odour. 



34.— Examine the sticky stem of the Catchfly. What causes the stickiness? What is its i^iob- 

 able use ? 



