Simple Foi-ms of Life. 201 



mucous lining of the alimentary organs, passing through 

 animals of every degree of development, until the animal itself 

 becomes simplified to the degree of appearing as a mass of 

 gelatinous sarcode only, or with possibly a central nucleus of 

 membrane, as in Actinophrys sol," etc. 



The animalcules which the beginner will find in his col- 

 lections are all composed of sarcode, and the differences to be 

 observed amongst them concern first the degi-ee to which 

 a distinct integument exists, and secondly the character of the 

 organs or parts that can be seen in all but the most elemen- 

 tary and minute kinds. 



We shall have occasion to recur again to the animal series, 

 but it will be convenient to take a preliminary glance at some 

 simpler vegetable forms, and although the beginner in collect- 

 ing objects for the microscope is very likely to pass over the 

 amoebae he may acquire, he is sure to see plenty of quite a 

 different object, the euglena, a lively little green fish-like thing 

 that abounds in the green scum of ponds. When he sees this 

 creature swim rapidly hither and thither, lashing about the 

 filament which springs from its head and constitutes its organ 

 of locomotion, when he further beholds it change its shape, 

 now taper and spindle, now squat and pear-like, now round, 

 and so forth, who can doubt that a veritable animal is in view ? 

 Not so ; the euglena is merely a plant, and further inquiry will 

 show that it is not uncommon for simple plants, or for their 

 spores, to possess cilia, and exhibit what is easily taken for 

 voluntary motion. 



The possession of a cilium, of which a vibratile filament may 

 be taken as a modification, gives no clue to the animality or 

 vegetality of the object employing it. A cilium may be an 

 organ of voluntary or involuntary motion. We find it con- 

 tinually moving, through mere physical stimulus, in creatures 

 of both high and low organization, or, as in the tentacles of a 

 rotifer like Stephanoceros, evidently under the command of a 

 will directed by a noticeable amount of intelligence. 



When a swarm of euglenae and other infusoria move 

 quickly through the field of the microscope, we have a (rela- 

 tively) powerful lashing of whips and twirling of cilia, without 

 a single muscle to do the work. Thus the contemplation of a 

 few simple microscopic forms has introduced us to locomotion 

 without limbs (as in the amoeba), sensation (of some kind) 

 without nerves, ingestion of food without a mouth, digestion 

 without a stomach, and active exertion, with motion of ap- 

 pendages, without a muscle to do the work. It is like the 

 German story, in which the blind man shoots a hare, a lame 

 one runs after it, and a naked one puts it in his pocket.* 

 * Kinder und Hausmarchen " Knoist un sine dre Suhne." 



