200 PRACTICAL BOTANY, 



t 



Bower's " Practical Botany," pp. 287-318 ; Huxley and Martin's " Ele- 

 mentary Biology," pp. 443-459 ; Arthur, Barnes, and Coulter's " Plant 

 Dissection," pp. 103-129 ; Dodge's " Practical Biology," pp. 320-335 ; 

 Strasburger and llillhouse's "Practical Botany," pp. 287-297; Car- 

 penter's " The Microscope," pp. 599-605 ; Underwood's " Our Native 

 Ferns and Their Allies " ; Atkinson's " Biology of Ferns " ; Strasburger, 

 Noll, Schenck and Schimper's " Lehrbuch der Botanik," pp. 349-372. 



FIG. 128. Equisetum arvense. 1, a barren plant ; 2, fertile plant ; 3, a spike 

 of sporangiophores of Equisetum arvense ; 4, a single sporangiophore ; 5, a 

 spore with elaters extended ; 6, spore with elaters wrapped around it ; 7, 

 a fertile plant of Equisetum sylvaticum; 8, a prothallium of Equisetum. 

 (After Kerner and Oliver.) 



CLASS II. The Horsetails (ISquisetince). There is now 

 only one order in this class, and this is homosporous. 



