M I in- | 



I Q} I -I I \« I I 





Ordrr Will. ' , 



.jniart II 



■ 



Diagnosis. Sport ■ • 



branched plants with a Btriated fistular stem, in the c 

 . ; the articubi id surrounded by a membra 



a fistolar, with many Longitudinal cavities in it- circum- 

 ference ; ehieflj ibstance, bul 

 externally with a layer of bard woody tubes, from which pla 

 of a similar nature project towards the centre, partially divid- 

 ing the longitudinal cavitit a from each other. - ar- 

 ranged longitudinally on the cuticle. Spiral w ry small 

 tut abundant Spo re-cases opening inwards by a longitudinal 

 slit, atta h< 1 to the lowi f peltate scales, which are col- 

 lected iiii. i terminal con< a. Spores, ■ ■% :il grains, wrapped round 

 with a pair of highly elastic clavate dab 



ibte plants known by the vulgar name of Horse- 

 tails, Beeni to have no very decided affinity to any existing 

 order. With Ferns their relation is not obvious. In the ar- 

 rangement of their reproductive organs they have a striking 

 resemblance to Zamia,and in their gent ral aspi ct to Ephedra i r 

 Casuarina. Their germination is that of Cellular plants, and 

 approaches nearly to Drnmosses. The structure of th< Lr Btem 

 i- will described by Ad. Brongniart in his /. 

 r - are, indeed, other parts of their organisation : 



Tables 11 ami 12 of that work. This ingenious writer enter- 

 tains tli' "pinion that the green body, which is known ti> be the 

 Bpore, is a oak< 1 ovule, and the tour swollen filaments that sur- 

 round it four grains of pollen united in pairs to th< base ol the 

 ovule. In the last edition of this work [adopted M. Brongniart's 

 view, and accordingly placed Equisetum with Conifers, an ■ i • 

 bo ver) obvious, as to have called forth rebukes, which w< 

 riclily di si rved. The d< \ elopment of the swollen filaments has 

 refully observed by fifohl, Henderson, and others, who 

 have demonstrated that they are really produced by the spiral 

 splitting of the cell in which th« spore is formed ; in fact, they appear quii 



Mr. Griffith has stated, to the elatera ol Marchantiaand it- alli< -. to which U 

 hoars, perhaps, a ni arer relation than to any other plant, ro regard H 

 form of the Unseal alliance seems to me more 

 client than to station thorn with Perns and 

 Clubmosses, to which the) seem to have no 

 immediate affinity. The resemblance h>t" 

 the peltate Bcalea of Bquisetmn and the heads 



of spore-cases in Marchantia, i- t b\ ions not 



to strike the most unpractis d ol server. Link 

 calls these Bcales Spondoebia. 



Tin germination of the spa been ex- 



plained, both by Agardh and Bischoff. The 

 form describee it thus : from 



three to fourteen days after th wn, they send down a filii 



what clavate, simple root, and protrude a confervoid, cylindi 



torulose thread, either two-lbbed (in K. prati use) at tl 



Some days after, severa] branches grow out and 



body resembling a bundle of confervoid threads, 



The account of Bischoff (2V . .1 - 



he finds the confervoid thr 



I \ >;iW. 



^ 



KL1I. 







• 





1 \I.lll. 





