266 THE MICROSCOPE. 



powers are the same by which perfection is first achieved, and by 

 which, when lost, it is recovered. Indeed, it would almost seem as if 

 the species that have the least means of escape or defence from mutila- 

 tion, were those on which the most ample power of repair has been 

 bestowed, an admirable instance, if it be only generally true, of the 

 beneficence that has prepared for the welfare of even the least of the 

 living world, with as much care as if they were the sole objects of the 

 Divine regard." 



The primordial cell-wall of each cell does not appear to enter into 

 the formative process of the embryo the cell-contents alone nourish- 

 ing the vital blastema of the nucleus. A gradual cycle of progressive 

 development, once set up, goes on until the animal is sufficiently ma- 

 tured to break through the cell-wall, and thus escape from the ova-sac. 

 At the same time, it may be inferred, that all this is in some measure 

 aided by the process of endosmose ; and in this way certain gases or 

 fluids may become drawn into the interior, and thus aid in the supply 

 of nourishment for the growth of the animal. 



The cell-wall would appear to bear the same relation to the future 

 perfect animal, that the egg-shell of the chick does to it; it is, in 

 fact, but an external covering to a certain amount of gaseous and 

 fluid matter, thus placing the germ of life in a more favourable state 

 for development, assisted, as it is known to be, by an increase of tem- 

 perature, usually the resultant of a chemical action, set up or once 

 begun in an organism and a m/edium. 



The ovum destined to become a new creature originates from a 

 cell, enclosing gemmules, from which its tissues are formed, and nu- 

 triment is assimilated, and which eventually enables the animal to 

 successively renew its organs, through a series of metamorphoses that 

 give it permanent conditions, not only different, but even directly con- 

 trary to those which it had primitively. 



" Oh, there are curious things of which men know- 

 As yet but little ! secrets lying hid 

 Within all natural objects. Be they shells, 

 Which ocean flingeth forth from off her billows 

 On the low sand, or flowers, or trees, or grasses, 

 Covering the earth ; rich metals or bright ores, 

 Beneath the surface. He who findeth out 

 Those secret things hath a fair right to gladness ; 

 For he hath well performed, and doth awake 

 Another note of praise on Nature's harp 

 To hymn her great Creator." 



The Structure of Shells. We may exhibit the structure of shells by 



