230 SOT ANT. 



profusely after fruiting, and persist all summer ; and the Seouriug- 

 Rush, called also Dutch Rush (E. hiemale), with harsh green branch- 

 less stems which produce cones, and survive the winter. 



In ancient geological times the Calamites and their allies consti- 

 tuted a distinct oi'der (Calamarieae) of tree-like plants | metre in 

 thickness and ten metres in height. 



Practical Studies. — {a) Collect in early spring a numher of cone- 

 bearing stems of the common Horsetail. Note the joints (nodes), 

 bearing whorls of united flat leaves, and the cone, composed of whorls 

 of shield-shaped leaves. Split the cone and stem and note that the 

 latter is hollow, with closed nodes. 



(6) Carefully dissect out a single shield-shaped leaf from the cone, 

 and examine it, using a low power. Note the sac-shaped spore-cases 

 upon the under side of the leaf. Mount some of the spores dry, 

 using no cover-glass, and examine with the ^-inch objective. 

 Breathe upon the spores -oery gently to moisten them, and notice the 

 coiling of the elaters ; observe the quick uncoiling which takes place 

 upon the evaporation of the moisture. 



(c) Sow a quantity of the fresh spores upon moist earth or porous 

 pottery, covering with a bell-jar and taking every precaution to secure 

 constant moisture. The spores will begin to germinate in a few 

 days, when studies of successive stages of growth may be taken up. 

 By care the mature sexual plants (prothallia) may be grown, and the 

 antherids and archegones studied. 



(d) Make very thin cross-sections of the stem of the common 

 Horsetail. Note the position of the fibro-vascular bundles. Now 

 make vertical sections of the bundles and study the tissues, using 

 high powers. 



(e) Study the breathing-pores on the green stems of the common 

 Horsetail. Compare these with those of the Scouring-Rush. Study 

 also the disposition of the chlorophyll-bearing tissue in cross-sections 

 of both stems. 



(/) Examine underground stems of Horsetails, and compare the 

 structure with that of the aerial stems. Make cross sections of the 

 roots which are attached to these underground stems. 



Systematic Literature. — Underwood, Our Native Perns and Their 

 Allies, 67-70. Gray, Manual of Botany, 675-677. pi. 21 (6th edi- 

 tion). Baker, Handbook of the Fern Allies, 1-6. 



Class 13. LYCOPODiif.ffi;. The Lycopods. 

 428. The plant-body of the asexual stage consists of a 

 solid, dichotomously branched, leafy, and generally erect 



