CRYTOGAMIA EQUISETACE^. 7 



trary, their longitudinal vessels of small 'calibre are collect- 

 ed into fascicles placed in the midst of a cellular tissue uni- 

 form throughout. In the Pteris aquilina the tubes form 

 several winding and unequal fasciae, distinguished by their 

 lighter colour and irregular distribution, PL V. Fig. c ; in 

 the common Aspidia they are collected into circular bun- 

 dles, the two towards the groove of the stalk being much 

 larger than the others, which are placed near the outer 

 edge (Fig. d) ; and each bundle is separated from the cellu- 

 lar tissue by a dark brown corneous sheath, loosely connect- 

 ^d both with the tubes and the cellular parenchyma*. Ferns, 

 then, in their structure resemble the stalks of the herba- 

 cious Dicotyledones ; and the grooved stem, and the man- 

 ner in which the vessels ramify through the leaf, support 

 the analogy, brought still closer by the observations of Da 

 YULE on the germination and evolution of their seeds. 

 Edin. Encydop. ix. 327. 



3. E. arvense, stem smooth, furrowed; furrows about 10; sheaths 

 about 10, cleft; branches 8-10 in a whorl, rough, long, simple or 

 branched, square : fertile stem unbranched, with distant deeply- 

 toothed sheaths. 



Hal. Moist cultivated fields, too common. May. If. 



" It is a troublesome plant in pastures, and disagreeable to 

 cows, never touched by them unless compelled by hunger, 

 and then bringing upon them an incurable diarrhoea. It 

 does not seem to affect horses or sheep ;" LIGHT FOOT yet 

 said to be especially unwholesome to swine. 



4. E. palustre, stem deeply furrowed ; furrows about 8 ; sheaths 

 with about 8 lanceolate teeth ; branches 4-8 in a whorl, simple, 

 erect, roughish, pentangular. 



Hob. Spongy watery places, frequent. June, July. 2/ 



Every seedW an Equisetum is encompassed with 4 spiral fila- 

 ments attached to its base, which curl and twist about, 

 from their hygrometric property, in a very curious man^ 

 ner, and move the seed along with them in various direc- 

 tions. If a spike, when ripe in spring, be shaken over a 

 piece of white paper, the seeds will fall out in form of a 

 fine brown powder; and if they be damped a little by 



* The figures referred to the first attempts of the artist in engraving give but 

 a faint idea of the beauty of the structure describe^ or of the drawings frora which 

 they were copied. 



