go THE OLIVE LEAF. CHAP. 



equidistant teeth, cloven half-way down, which stand 

 upright and look like an elegant fringe. The purpose 

 of these teeth, which have the power of contracting and 

 expanding and fit into each other from opposite sides, 

 is to close up the orifice in damp or rainy weather, so as 

 to keep the precious contents dry and warm till the sun 

 again shines, when they speedily open and resume their 

 original upright position. One can see this wonderful 

 mechanism in operation at any time, by simply breathing 

 upon the fringe of teeth or applying a little moisture to 

 them, when they fall down and form a wheel-like lid of 

 many spokes, completely closing the mouth of the seed- 

 vessel ; expanding immediately when exposed to the 

 sunshine, or as soon as the moisture is dried up, and 

 standing round in an upright position like watchful 

 sentinels ready to do their duty. In addition to this pre- 

 caution, at an earlier stage of growth, the little central 

 column in the interior of the seed-vessel, around 

 which the seeds are clustered, is endowed with the same 

 sensitiveness to the condition of the weather ; in a dry 

 state of the air stretching and turning itself in a spiral 

 manner so as to raise the lid, which at this period 

 covers the seed-vessel, thus letting in the air and warmth, 

 but collapsing immediately should the air become damp, 

 so as to close the orifice securely and protect the seeds 

 from injury. 



T. The most curious thing about the teeth of mosses 

 is that they are either four in number, or constitute 

 some multiple of four. In every moss the number of 

 teeth is invariably one or other of the following series : 



