EQUISETUM. 
283 
are contained, as well as to assist in the dispersion of these 
minute reproductive bodies. They are, indeed, so irritable 
that a change of temperature or moisture, such as that 
produced by breathing on the spores, is sufficient to pro- 
duce this forcible uncoiling. The spores themselves are 
very interesting microscopic objects ; indeed, it is only 
under a high magnifying power that their nature can be 
examined. 
The germination of the spores has been made the sub- 
ject of experiment by several inquirers, whose observations 
have been published. Agardh states, that from three to 
fourteen days after the spores are sown, they send down a 
thread-like transparent root somewhat thickened at the end, 
and protrude a confervoid, cylindrical, obtuse, articulated, 
torulose thread, which is either two-lobed or simple at the 
apex. Some days after this, several branches are produced, 
and become agglutinated together, forming a body resem- 
bling a bundle of confervoid threads, each of which pushes 
out its own root. Bischoff finds these confervoid threads 
go on growing and combining until a considerable cellular 
mass is formed. Then this mode of development ceases, 
and a young bud is formed, which produces the stem of an 
Equisetum, at once completely organized, with its air-cells.; 
