NATURAL HISTORY RECREATIONS. 81 



has demonstrated that those minuticB of creation, notwithstanding their 

 minuteness, are not so simple in their organization, as has been gener- 

 ally supposed. 



If animal or vegetable substances are allowed to decompose in wa- 

 ter, in a few days, according to the temperature, there will be developed 

 uncounted numbers of these infusories. If you put a drop of the wa- 

 ter under a good microscope, you will observe a number of small points 

 moving among each other with the greatest rapidity, whilst larger ones 

 are seen leisurely swimming about. Similar bodies are found in the 

 green slime which is attached to plants, stakes, stones and other ob- 

 jects in stagnant water. At first, these little animals were considered 

 as inorganic globules or minute aquatic plants, which floated in the wa- 

 ter, and their motion was occasioned by the evaporation of the water. — 

 But closer research and numerous experiments have proved that these 

 microscopic bodies are really animals. Their motions are too various 

 and irregular to be explained by mere attraction or repulsion and other 

 physical causes. Besides, in many of them there has been observed a 

 complete organization, a mouth, intestinal caial, a shell enclosing the 

 body, and other physical members. As respects their motion, they swiftly 

 shoot forward, suddenly stop, turn round, move out of the way of others, 

 describe a circle, leap, lengthen themselves out, draw themselves in, be- 

 come narrow and then wide, and change their form in many curious 

 ways. The motion of some of the Infusories is very slow, often 

 scarcely observable to the eye, and these are frequently united together 

 in series. The existence of a mouth and intestinal canal was discov- 

 ered by Ehrenberg by coloring the water with indigo or carmine, which 

 was afterwards visible in the transparent body of the animals, showing 

 that they had swallowed it. By means of the hairs or ciliae by which 

 many of them are surrounded, the larger species often create an eddy 

 or rotary motion in the water, by which other smaller species are drawn 

 into their mouths. 



Their bodies consist entirely of uniform slimy substance, and are of 

 various forms. Some are oval, others globular, others flat, others cylin- 

 drical. The globular species turn on their own axis, and do not un- 

 dergo much variation in form. The flat ones move in .straight lines, but 

 often change their direction ; often they stretch themselves out and then 

 roll themselves up like a ball. The cylindrical often assume the shape 

 of an S or an 8, and then again suddenly stretch themselves out. For 

 the most part, the body is naked : but many are covered with a tender 

 shell or case : many have a tail consisting of sections that can be shov- 

 ed into each other like the pieces of a telescope; others liave a so-cal- 

 11 



