SPOKES AND SACS OF CLUB-MOSS. 187 



dium powder bums in a candle with an instant flash, and 

 being not readily affected by water is used by chemists for 

 coating pills. 



In the Coal Age there flourished giant relations of the 

 little club-moss, forest trees in fact, some of them a 

 hundred feet high, which might easily have been mistaken 

 for pine trees. Their cones, or rather catkins, did not, 

 however, produce seeds, but the leaves composing them 

 bore on their surfaces little sacs, or cases, scarcely larger 

 than those of the present club-moss, and, like them, filled 

 with spores. 



A thin slice of coal under the microscope is seen to 

 contain multitudes of yellowish-brown bodies, about the 

 twentieth part of an inch in diameter, which are flattened 

 bags, often filled with irregularly rounded hollow bodies, 

 measuring about one-seven-hundredth part of an inch 

 across. These are the spores and their cases, which form 

 by far the larger part of all the English bituminous coal 

 examined by Professor Huxley, and contribute mainly to 

 its inflammable character. 



Clouds of yellow dust may be shaken from a branch 

 of club-moss, and on the shores of some of the Canadian 

 lakes there are often great heaps of yellow pollen which 

 has been blown from the pine-forests, and being too 

 light to sink, has been thrown up on the muddy shore 

 by the waves. If this should ever be consolidated it 

 would form, with the mud, a sort of shale very similar to 

 an ancient deposit on the shore of Lake Huron, which is 

 so full of spores and cases that it burns readily with a 

 bright flame. (Fig. 37.) 



