352 



PART IIT. THE CLASSIFICATION OF PLANTS. 



7. 



8. 



9. 

 10. 

 11. 

 12. 



Series II. ACKOGYN.E : growth in length arrested by the development of 



archegonia ; all foliose. 

 Fam. 6. Gymnomitriece : Gymnomitrium, Sarcoscyphus (Marsupella) , 



Alicularia (Nardia), etc. 

 Jungermanniea; : Plagiochila, Jungermannia, Lophoco'ea, 



Scapania, etc. 



Geocalycece : Saccogyna, Calypogeia, etc. 

 Trichomauoidece : Lepidozia, Mastigobryum, etc. 

 Ptilidea : Tricbocolea, Ptilidiurn, Seudtnera, etc. 

 Platyphyllea : Kadula, Madotheca. 

 Jubulece : Phragmicoma, Lejeunia, Frullania, etc. 

 Order III. Anthocerotaceae. 



A. The GAMETOPHYTE. The protonema developed from the germinating 

 spore is a flattened plate of cells; in Authoceros the formation of the flattened 

 plate is sometimes preceded by the outgrowth of the contents of the spore, 

 covered by the endosporium, into a filament at the apex of which the plate of 

 cells is developed ; in Dendroceros the first cell-divisions connected with the 

 formation of the protenema frequently take place widiin the spores before they 

 are shed from the sporogonium. The adult shoot 

 is developed as a lateral out-growth from the 

 flattened protonema. 



The Morphology of the adult shoot. The adult 

 shoot is thalloid, and its symmetry is dorsi ventral. 

 It is semi circular, or nearly circular, in outline in 

 Anthoceros and Notothylas; but in Dendroceros it 

 is elot'gated and branched, in which genus it has a 

 strongly developed midrib which projects especially 

 on the ventral (under) surface. There are no ven- 

 tral scales on the under surface, but numerous uni- 

 cellular root-hairs. 



The growth of the shoot is effected, in Anthoceros and Notothylas, by a series 

 of marginal growing-points ; in Deudroceros, by a growing-point at the apex of 

 the main shoot and of each of its branches. In the growing-point there is a 

 row of initial cells, each of wbich acts as an apical cell ; their form is wedge- 

 shaped in Anthoceros, dorsal and ventral segments being alternately cut off by 

 the formation of oblique walls; in Dendroceros their form is nearly hemi- 

 spheral, the base being internal, and segments are cut off by the successive 

 formation of transverse walls at right angles to the long ax : s of the shoot. 



Branching, or at least the formation of new growing-points, takes place in 

 the manner described for the Marchantiaceae (p. 184). 



The sexual organs are developed from the dorsal segments formed in the 

 growing-point, and are situated in the middle line behind each growing-point 

 in Anthoceros and Notothylas. on the midrib in Dendroceros. The antheridia, 

 which have a long stalk in Dendroceros, are developed endogenously, and remain 

 enclosed in the tissue until maturity ; they are developed either singly (some 

 species of Anthoceros, Dendroceros) or in groups. The archegonia are sunk in 

 the tissue, the apex of the neck reaching to the dorsal surface of the shoot. 

 The shoots are monoecious ; the sexual organs are sometimes intermingled in 

 the same group (frequently in Anthoceros). 



FIG. 246. Anthoceros Icevis 

 (nat. size). K The capsules, 

 some as yet unopened. 



