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result. Thus a fern has a dual existence, one generation 

 only developing spores, and the other the organs of repro- 

 duction. This is called the Alternation of Generations. 

 In the Fir tribe there are both micro and megaspores; 

 the former dusty, and very like the spores of ferns, the 

 latter are larger, and formed on the bracts of the cones. 

 The megaspores are not shed, but each develops a minute 

 prothallium within the spore; on this is developed the 

 germ which will be fertilised by a microspore, and will 

 then grow into an embryo or seed of the Fir. In flower- 

 ing plants the same takes place, only the prothallium is 

 reduced to a few obscure cells. So in these instances the 

 spore-producing generation is the important one, and the 

 reproducing generation is insignificant. 



In mosses the reverse is the case. The Moss-plant 

 develops the organs of reproduction, fertilisation takes 

 place, and the embryo develops into a single spore-pro- 

 ducing case, which is generally on a tall stalk, and lives 

 permanently attached to, and deriving its nourishment 

 from, the mother plant, and is called its fruit. 



In the days of old but little interest was taken in the 

 study of plants, though a greatly exaggerated idea of medi- 

 cinal properties gave work to primitive physicians known 

 as herbalists. Those who pursued them had to confine 

 their studies to external characters becaxise they had little 

 means of seeing further. With the advent of the micro- 

 scope this was changed, and earnest students soon took 

 advantage of this instrument to unravel the mysteries that 

 existed beneath the surface. 



One of the first things noted was that when a transverse 

 section of a plant-stem was made, the appearance it 

 assumed had somewhat that of a minute honeycomb. It 

 seemed to be made up of small chambers. These were 

 filled with fluid, but that received no attention, and the 

 plant was considered to be made up of these chambers 

 which had the ability of growing and multiplying. As 

 the spaces in a honeycomb were called cells so these spaces 

 in the plant tissue received the same name. Even to the 

 present day the name has survived for the ultimate 

 structure of plants and animals, though its meaning has 

 long since passed away. 



In the fullness of time it was discovered that the cell- 

 walls were simply non-living cases, and the viscid fluid 

 contained was the true living substance. We know now 

 that this viscid fluid is a highly complex material com- 

 pounded of hundreds of atoms of some ten different ele- 



