Il8 THE DAWN OF LIFE 



we consider the startling character of the facts adduced, and 

 has mostly come from men imperfectly informed. 



But what is Eozoon, if really of animal origin ? The shortest 

 answer to this question is, that this ancient fossil is supposed 

 to be the skeleton of a creature belonging to that simple and ^ 

 humbly organized group of animals which are known by the 

 name Protozoa. If we take as a familiar example of these the 

 gelatinous and microscopic creature found in stagnant ponds, 

 and known as the Amoiba ^ (Fig. 8), it will form a convenient 

 starting-point. Viewed under a low power, it appears as a 

 little patch of jelly, irregular in form, and constantly changing 

 its aspect as it moves, by the extension of parts of its body into 

 finger-like processes or pseudopods which serve as extempore 

 hmbs. When moving on the surface of a slip of glass under 

 the microscope, it seems, as it were, to flow along rather than 

 creep, and its body appears to be of a semi-fluid consistency. 

 It may be taken as an example of the least complex forms of 

 animal Hfe known to us, and is often spoken of by naturalists 

 as if it were merely a little particle of living and scarcely organ- 

 ized jelly or protoplasm. When minutely examined, however, 

 it will not be found so simple as it at first sight appears. Its 

 outer layer is clear and transparent, and more dense than the 

 inner mass, which seems granular. It has at one end a curious 

 vesicle which can be seen gradually to expand and become 

 filled with a clear drop of liquid, and then suddenly to contract 

 and expel the contained fluid through a series of pores in the 

 adjacent part of the outer wall. This is the so-called pulsating 

 vesicle, and is an organ both of circulation and excretion. In 

 another part of the body may be seen the nucleus, which is a 

 little cell capable, at certain times, of producing by its division 

 new individuals. Food, when taken in through the wall of the 

 body, forms httle pellets, which become surrounded by a 



* The alternating animal, alluding to its change of form. 



