THE BAY OF BISCAY. 233 



secure the perpetuity of species? and let us be 

 careful in this investigation not to separate plants 

 from animals, for in the two kingdoms of nature inert 

 matter after being vivified by life rises to a state 

 of organisation under the control of the same laws. 



Every living being is produced from an egg, or, to 

 adopt the axiom of Harvey, omne vivum ex ovo. If 

 by this word we understand something that is always 

 identical with and more or less similar to the egg of 

 the . bird, the inaccuracy of the aphorism would be 

 evident. A plant is multiplied by seeds, buds, 

 bulbils, cuttings, &c., and animals present to us 

 precisely analogous facts. If, for instance, we take 

 one of those fresh- water Hydras, which are so common 

 in our ponds, and cut it in pieces, we shall find in 

 the course of a few days that each fragment has 

 become a complete individual. This is a reproduc- 

 tion by cuttings. If we observe the same Hydra in 

 the vessel into which we have thrown for its nourish- 

 ment the larvae of Insects or of Naides, we shall per- 

 ceive that at one time it will lay eggs covered by a 

 solid shell, that is to say, it will produce true animal 

 seeds ; while at another time it will give off buds, 

 which grow, become more and more organised, and 

 at length appear in the form of a young Hydra fur- 

 nished with all its organs. At first adherent to the 

 parent, and in direct communication with it, this 

 newly formed being in all respects resembles a para- 

 site, and is like a tender branch which derives all its 

 nourishment from the trunk. After a few days, 

 when the mouth is formed and the arms have grown 

 longer, the young Hydra begins to seek for prey on its 



