8 Practical Exeucisks. 



20. — Detach with the 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 flower of 

 Milkweed. 



21. — Obs<»rve whether insects visit the flowers of any of the following : Piiu-, Willow, Cucumber, 

 Maple. 



'22.- Mak»- 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 upon the seeds of Milkweed 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. 



2ti. — Gather a few acorns and seeds of the Red Maple and lay them away for the winter. In tlie 

 spring test their germinating powers. 



27 — Examine scales of green pine-cones, and also of v\\>e ones. 



28. — Study the dehiscence of the ovary in Purslane, Sliepherd's Purse, Catchfly, Columbine, Mallow, 

 Morning Glory. 



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



;•<! Observe through a good microscope, and make drawings of : — 



(aj Six different pollen-grains. 



(bj A thin slice of Elder pith. 



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



(d) A similar shred from the upper surface. 



'''■ ' A cross-section of a bit of Lilac leaf with a vein in it. 



,_/ , A plant-hair. 



(g) A vertical section through the tip of a rootlet. 



i'h I A thin slice of Potato. 



' Tlu- }»loom on a CaVibuu'f-U'uf 



■> I . Make cross-sections of the Buittlioo and a branch or small stem of any of our native woods. 

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



32. — Examine the Viark of a young 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 microscoi»e. Give your 



opinion of the source of its o<lonr. 



.'M —Examine th»> «tirkv ^trm ..f tl,f> fatchfly. What causes the stickiness? What is its prob 

 able u^e ? 



