1 8 , Marvels of Pond-Life. 



theory to the dubious objects which lie on the border- 

 land of the animal world, and no other theory that has 

 been propounded appears to meet all cases. Some 

 naturalists do not expect to find a broad line of de- 

 mark ation between the two great divisions of living 

 things, but others characterise such an idea as " un- 

 philosophical/' in spite of which, however, we incline 

 towards it. 



Mr. Gosse, whose opinion is entitled to great respect, 

 calls the Euglence C( animals " in his ' Evenings with 

 the Microscope/ but from the aggregate of recorded 

 observations it seems that they evolve oxygen, are 

 coloured with the colouring matter of plants, reproduce 

 their species in a manner analogous to plants, and have 

 in some cases been clearly traced to the vegetable 

 world. It is, however, possible that some Euglence 

 forms may be animal and others vegetable, and while 

 their place at nature's table is being decided, they must 

 be content to be called Phytozoa, which, as we have 

 before explained, is merely Zoophyte turned upside 

 down. 



Some authorities have thought their animality proved 

 by the high degree of contractility which their tissues 

 evince. This, however, cannot go for much, as all 

 physiologists admit contractility to belong to the vege- 

 table tissues of the sensitive plant, " Venus' Fly-trap/' 

 &c, and a little more or less cannot mark the boundary 

 between two orders of being. 



We shall have occasion again to notice the Proto- 

 phytes, and now pass to the Protozoa, of which we have 

 a good illustration in the Vorticella already spoken of. 



