TRANSITORY CONDITIONS OF LIVING BEINGS. 277 



and to increase into a leaf-like expansion, very much resembling 

 that of the Marchantia. In the middle of this (which has 

 received the name of primary frond), a knot or protuberance 

 gradually makes its appearance; and this is afterwards pro- 

 longed above into a sort of stem, and below into a root. From 

 this stem, the true leaves or fronds are afterwards developed, 

 unrolling themselves after the manner formerly described (. 25); 

 and, when these make their appearance, the primary frond 

 decays away, leaving no traces of its existence. In this very 

 curious process, we see that the Fern passes, as it were, through 

 the stage which is permanent in the Marchantia ; but that when 

 it attains a higher form, the organ, which was only for a time 

 subservient to its existence, decays away. 



431. Many instances of a similar kind present themselves in 

 the Animal kingdom. Thus the Frog comes forth from the egg 

 in a state resembling that of a Fish, breathing by gills instead 

 of by lungs, possessing a long tail by which it moves itself in 

 the water, and destitute of legs. Subsequently legs are produced, 

 which render its tail unnecessary ; and lungs are developed, 

 which perform its respiration more effectually than gills ; and 

 the first two sets of organs, though they permanently exist in 

 Fishes, disappear in the Frogs, as soon as they have served their 

 temporary purpose. Corresponding changes, hardly less striking 

 than this, take place during the development of every one of the 

 higher Animals ; and in every instance we see that, when a 

 higher form is attained, the parts which had their uses in an 

 inferior condition of existence, are cast off as cumbrous and 

 unnecessary. How beautifully does this principle apply to the 

 history of the development of the Human soul ! At first it is 

 entirely dependent for its activity, on the impressions which it 

 receives through the bodily frame, with which it is connected. 

 The calls of hunger, the presence of unaccustomed objects, strong 

 impressions upon its senses, first excite its attention ; and all its 

 subsequent acquisition of knowledge, depends upon similar in- 

 fluences. Perfect in their kind as are the organs of sensation, by 

 which these impressions are communicated, there are still bounds 

 to their operation. All that their highest exercise, with the aids 

 derived from the most refined ingenuity, can effect in this life, 



