MINUTE AQUATIC ANIMALS. 65 



CHAPTER III. 



MINUTE AQUATIC ANIMALS. 



" Then sweet to muse upon His skill displayed 

 (Infinite skill) in all that he has made ! 

 To trace in nature's most minute design, 

 The signature and stamp of power divine : 

 Contrivance intricate, expressed with ease, 

 Where unassisted sight no beauty sees; 

 The shapely limb and lubricated joint 

 "Within the small dimensions of a point; 

 Muscle and nerve miraculously spun, 

 His mighty work who speaks and it is done." COWPER. 



THE POLYPE. This singular animal, of which there are several species, is 

 found abundantly in ponds and brooks, attached to the leaves of aquatic plants, 

 and to the surface of twigs and branches that have fallen in the water. Its body, 

 which simply consists of a collection of cells, formed of grains of green and 

 brown matter, possesses the power of expansion and contraction, and appears, 

 when extended, in the shape of a jelly-like tube, about the size of a bristle ; 

 tapering from the upper to the lower extremity, and having a length ranging 

 from one-quarter to three-quarters of an inch. The mouth is furnished with 

 feelers or arms, which vary in number, in different specimens, from six to sixteen, 

 and are employed by the animal for the purpose of seizing its food. Though 

 appearing to the unaided eye as attenuated threads, the microscope shows them 

 to be, in fact, slender tubes filled with a fluid, and consisting of a series of cells like 

 the body of the animal. When contracted the polype appears like a tiny 

 ball of jelly, hardly one-tenth of an inch in diameter, and the long arms or 

 feelers shrink into little conical eminences, ranged in a circle around the upper 

 part of the body. 



Figures 97, 98, 99 and 100 present a magnified view of several polypes, in 

 different states of contraction, with their prey within them. A species, termed 

 from its color the Green polype, is delineated in figures 97 and 98 and another 

 kind, the Brown polype, is represented in different attitudes in figures 99 and 100. 

 The small circles exhibit the specimens of their natural size. The mouth of the 

 polype is unfurnished with teeth, and presents different appearances, according as 

 it is more or less contracted ; at one time assuming the form of a cone, and at an- 

 other appearing cup-shaped, with an aperture in the centre, capable of great ex- 

 pansion for the reception of its food. This last form is shown in figure 98, 

 where the animal is seen gorging its prey. The polype feeds upon small crustace- 

 ous animals, worms and Iarva3 ;* and when in search of food extends its body and 



* Larvae are the young of insects in their caterpillar state. 

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