18 
INTRODUCTION. 
confirm the above view, and give also the origin of the minute grains found upon 
the elaters or elastic filaments ; from this paper, it appears that when the integu- 
ment of the spore shows the spiral lines, which it will afterwards break into the 
elaters, it contains a greenish-coloured fluid, mixed with some minute granules. 
The spores then become darker, the granules increase, the liquid is absorbed, 
leaving the granules which it contained sticking in masses to the spores, and to 
the separated portions of the integument. It is these masses of granules, when 
found adhering to the filaments in the ripened state of the spore, that have been 
taken for pollen-grains, and such the observations of the author prove them to 
be. He says (p. 571) — “On comparing these granules with those contained in 
the unopened anthers of flowering plants, they appear to me to be in every 
respect identical ; in the theca; they seem to occupy a similar place with those in 
the cells of the anthers, and they decrease in like manner during the progress to 
maturity of the pollen-grain and of the spore.” 
DISTRIBUTION. — “Nearly equal in number with the Lycopodiacere, the 
plants included under this order contrast against them in their distribution. 
Whilst the former arc described in general terms as plants of the moors and 
mountains, the Equisetacea; belong more especially to marshes, fields, and 
woods. Both orders, or genera, are alike widely distributed through Britain ; 
but whilst the Lycopodiums prevail high on the mountains, the Equisetums 
are more abundantly bestowed upon the lower grounds, or the plains and valleys > 
the latter also evince more of a maritime, or even littoral tendency than the 
Lycopodiums, being often seen in abundance on and near the sea-shore.” — 
Mr. Watson's MS. 
USES. — They are harmless to cattle, but refused on account of their husky, 
rigid texture. They are useless as medicines, but employed in the arts ; their 
silicious cuticle rendering them valuable as polishing substances for marble, wood, 
ivory, and even metals. 
