MANUAL OF NATURAL HISTORY. 529 



have actually traced this strange transformation, so 

 that certain minute existences are, at one portion of 

 their life animal, and at another, vegetable. Such no- 

 vel speculations may, perhaps, be ascribed to the ac- 

 knowledged difficulty of ascertaining what is the 

 essential characteristic which distinguishes two, ap- 

 parently similar, vivified globules, what it is that 

 determines the one to be phytous and the other 

 zoous. And yet that such a primary separation 

 exists in reality, though not easily appreciable to 

 our senses, can hardly be doubted, when we see 

 their varied effects. That many of the simpler 

 orders should at different times be looked upon 

 either as plants or as animals, is easily to be ac- 

 counted for, according to the view of the observer, 

 but that the two are connected by direct transition, 

 seems not probable, as their vitality differs not only 

 in degree, but also in kind. The one more sthenic, 

 more intense, giving tone to the fibres, and irrita- 

 bility to the nerves, capable of producing quicker 

 and more marked effects, but sooner wearing itself 

 out, and therefore less lasting, — the other more 

 chronic, more deficient in positive strength, but, often 

 more enduring, and adapted for supporting the more 

 simply constructed members of the Vegetable World. 

 The marks of animal life have already been al- 

 luded to at page 2, so that it is merely requisite to 

 say, in addition, that recent researches have shewn 

 that starch granules form part of the contents of 

 many cells, and when they can be detected, no 

 doubt need be entertained of the vegetable nature 



