EQUISETUM. 283 



are contained, as well as to assist in tlie 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, 

 torulosc 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 

 Eqidsetum, at once completely organized, with its air-cells.. 



