INTROD.] REPRODUCTION. ASSIMILATION. 1 1 



How beautiful is the provision which this power, possessed by 

 organized bodies, of generating others, affords, for preserving a per- 

 petual succession of living beings over the globe ! The command, 

 " Increase and multiply/' has never ceased to be fulfilled from the 

 moment it was uttered. Every hour, nay, every minute, brings 

 into being countless myriads of plants and animals, to supply in 

 lavish profusion the havoc which death is continually making ; and 

 it is impossible to suppose that the earth can cease to be in this 

 way replenished, until the same Almighty Power, that gave the 

 command, shall see fit to oppose some obstacle to its fulfilment. 



In addition to this power of propagation, organized bodies enjoy 

 one of conservation and reproduction. Solutions of continuity, the 

 loss of particular textures, whether resulting from injury or from 

 disease, can be repaired. Parts, that have been removed, may be 

 restored by a process of growth in the plant or animal, and in some 

 animals the reproductive power is so energetic, that if an individual 

 be divided, each segment will become a perfect being. This power 

 of reproduction is greater, the more simple the structure of the 

 organized body; the more similar to each other are the constituent 

 parts, the more easy will reproduction be. Numerous examples of 

 this power may be adduced, the healing of wounds, the adhesion 

 of divided parts are familiar to every one. New individuals are 

 developed from the cutting of plants : the division of the hydra 

 into two, gives rise to the production of two new individuals. If a 

 Planaria be cut into eight or ten parts, according to Duges, each 

 part will assume an independent existence. 



The power of reproducing single parts only, is possessed by 

 animals higher in the scale. In snails, part of the head, with the 

 antennae, may be reproduced, provided the section have been made 

 so as not to injure the cerebral ganglion. Crabs and lobsters can 

 regenerate their claws, when the separation has taken place at an 

 articulation ; and spiders enjoy the same power. In lizards, the 

 tail, or a limb, can be restored, and in salamanders the same phe- 

 nomenon has been frequently witnessed. 



Organized bodies can appropriate and assimilate to their own 

 textures other substances, whether inorganic or organic. This 

 process is that which is most characteristic of living creatures : in 

 virtue of it, animals and plants are continually adding to their 

 textures new matter, by which they are nourished. Plants ap- 

 propriate their nutriment from the inorganic kingdom, as well as 

 from decaying organic matter ; animals, chiefly from organic mat- 

 ters, whether animal or vegetable. Both possess the wonderful 



