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 
integument of the spore shows the spiral lines, which it will afterwards break 
into the elaters, it contains a greenish colored fluid, mixed with some minute 
granules. The spores then becomes 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 Lycopodiacese, the 
plants included under this order contrast against them in their distribution. 
Whilst the former are described in general terms as plants of the moors and 
mountains, the Equisetacese 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 abuudance 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. 
