The first impression of any casual observer would be to declare in favour of their animality; but before this can be settled, comes the question, what is an animal, and how does it differ from a vegetable? and upon this the learned do by no means agree. One writer considers the presence of _starch_ in any object a proof that it belongs to the dominions of Flora, while another would decide the issue by ascertaining whether it evolves oxygen and absorbs carbon, as most plants do, or whether it evolves carbon and absorbs oxygen, as _decided_ animals do. Dr. Carpenter asserts that the distinction between _Protophyta_ and _Protozoa_ (first or simplest plants and animals), "lies in the nature of their food, and the method of its introduction, for whilst the _Protophyte_ obtains the materials of its nutrition from the air and moisture that surround it, and possesses the power of detaching oxygen, hydrogen, carbon, and nitrogen from their previous binary combinations, and of uniting them into ternary and quaternary organic compounds (chlorophyll, starch, albumen, &c.), the simplest _Protozoa_, in common with the highest members of the animal kingdom, seems utterly destitute of any such power, makes, so to speak, a stomach for itself in the substance of its body, into which it injects the solid particles that constitute its food, and within which it subjects them to a regular process of digestion." Unfortunately it is very difficult to apply this simple 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 demarkation between the two great divisions of living things, but others characterise such an idea as "unphilosophical," in spite of which, however, we incline towards it. Mr. Gosse, whose opinion is entitled to great respect, calls the _Euglenæ_ "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 _Euglenæ_ 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 vegetable tissues of the sensitive plant, "Venus' Fly-trap," &c., and a little more or less cannot mark the boundary between two orders of being.