78 THE WOOD. 



and locality, they all agree in these respects they 

 are very tenacious of life, and exceedingly pro- 

 lific, in most cases producing abundance of seeds, 

 or, when they fail to do this, increasing rapidly by 

 means of their creeping stems. Their seed-vessels 

 are very singular, and, though minute, are very 

 complex in their structure. From amongst a set 

 of leaves, differing in shape from the rest, rises a 

 stem no thicker than a horse-hair, and extremely 

 tough, which, during the early stages of its growth, 

 tapers to a point. Soon the upper part begins 

 to swell, when it is found to be enclosed in a case, 

 shaped somewhat like a hood, either expanding as 

 the seed-vessel enlarges, or splitting down on one 

 side. As the seed-vessel approaches to maturity 

 the hood falls off", and within is discovered a beau- 

 tifully polished, urn-shaped vessel, either standing 

 erect on the summit of the stem, curved more or 

 less, or quite pendulous. It has its mouth closed 

 with a lid, which, when the seeds ripen, also falls off, 

 and exposes, in most cases, a single or double row of 

 threads, flattened at the base and tapering upwards, 

 which appear to be a continuation of the lining of 

 the seed-vessel. These threads, or " teeth," as they 

 are called, are always of the same number in the 

 same species of Moss, being either 4, 8, 16, 32, or 

 64. They are highly sensitive, altering their posi- 

 tion at every change of weather. During wet 

 weather they lie flat on the mouth of the seed- 

 vessel, and lock into one another in such a way 

 as to prevent a particle of moisture from reaching 

 the seeds. As soon, however, as the air becomes 

 dry, they rise and stand erect, or bend backwards 

 over the outside of the seed-vessel, allowing the 

 seeds, which are so minute as to be wafted away 



