OF ANIMATE BEINGS. 11 



pressed so closely to its surface as to project it more or less, and 

 thus they appeared to be a part of the body itself. The food, 

 which may be either a living animal or plant, is evidently in- 

 troduced into the body at any point, simply by being adhered 

 to by the viscous surface, and gradually engulfed in the trans- 

 parent sarcode, as this sort of structureless animal-tissue has 

 been called. 



Now what I wish particularly to draw your attention to, in 

 this somewhat minute description of the Amoeba, is that so ex- 

 ceedingly simple a structure should perform such a variety of 

 acts. It creeps and changes its form, which indicate a muscular 

 power ; and seeing that one end of the body always precedes 

 the other, it is fair to draw the inference that this muscular 

 power is under the directing control of at least a certain degree 

 of nervous sense. And again the introduction, circulation, and 

 digestion of food, and the final rejection of the harder indigest- 

 ible parts of the prey, all point unquestionably to a function 

 which is proper to animals and not to plants. There can be no 

 doubt, then, that this particle of slime-like matter, which is called 

 Amoeba, is an animal in the fullest sense of the term. 



These other three diagrams (figs. 2, 3, 4,) are intended to 

 illustrate the manner in which the complication 

 of the organization is brought about, as we rise 

 from the lowest forms of life, as represented by 

 the Amoeba, through the gradually more elevat- 

 ed types to the highest in this peculiar group 

 of beings. The first step in this advance is 

 made by the addition of a covering, of such a 

 form in this case as to restrict the prolongation 

 of the protrusile parts of the body to one re- 

 gion. In the figure before us, which is that of 

 a Difflngia, (fig. 2,) the body is enveloped in a 

 Fig-. 2. globular or pear-shaped membranous sac (a) 



Fig. 2. Diffluyia proteiformis. Ehr. 100 diam. A view from above, look- 

 ing down upon the top of the shell, a. b, the pseudopodia, projecting from 

 before and behind. The arrow indicates the flow of the granulated fluids of the 

 body. Original. 



