not only commences its existence as a tiny liitle sac, con- 

 taining a tiny quantity of liquid, which sacs are practically 

 indistinguishable as to form and composition, but is also 

 eventually constructed entirely by a succession of such 

 cells. From the bacterium to the whale or the colossal 

 redwood trees of Colorado is this the case, as well as with 

 all the infinitely diverse forms of life which lie between 

 these dimensional extremes as plants or animals. Further, 

 more, if we take intelligent stock of our surroundings we 

 shall find that the vast majority of the substances with 

 which we deal are derived from organic sources, and hence 

 have been built up at some period, remote or recent, by the 

 operation of these little constructive sacs or cells. 



Probably, to the lay observer, the fern spore presents 

 one of the easiest objects by means of which we may be 

 better enabled to grasp from start to finish the nature of 

 the work of which a simple cell is capable. The spore is 

 merely such a cell protected by a shell, and with a micro- 

 scope of moderate power it is fairly easy to watch its 

 operations from the moment when, under the influence of 

 moisture and warmth, it swells and bursts this shell and 

 emerges to the light. No sooner does this occur than a 

 very wonderful process begins, to understand which we 

 must for a minute or two consider that no mere sac of 

 jelly could do anything at all, unless within it were con- 

 tained some impulsive and directing power. Neither the 

 skin or the jelly possesses such power, but within the latter 

 there is always, in a living, active cell, a truly wonderful 

 little body, a bundle of fibres, called the nucleus, and it is 

 in this that the life principle lies which eventually deter- 

 mines, guides, and controls all the future operations which 

 result in the production of a new organism. Such a 

 " nucleus " is in the cell enclosed in the spore husk, and it 

 is this which, on the liberation of the cell, immediately 

 sets to work to perform its functions. The observation of 

 this stage is probably beyond the scope of the lay or 

 unscientific observer, but it may be taken for granted as 



