THE INFUSORIA. 



585 



It can elongate itself to almost any extent, can then throw out its strange protrusions so 

 as to resemble a club with a spiked head, or it can gather itself into a rude globular mass, as 

 if pinched out of dough by a single 

 squeeze of the hand, allowing the 

 soft substance to protrude between 

 the, fingers. It has no particular 

 stomach, but extemporizes that 

 organ out of any part of its body 

 with which its food happens to 

 come in contact, literally pushing 

 the food into its body and then 

 digesting it without requiring 

 any special apparatus for the 

 purpose. 



Some of the Lobose Rhizopods, 

 as these creatures are called, are 

 also furnished with a shelly or 

 horny covering, such as the Arcel- 

 lina, where the shield is cap- 

 shaped, or the Difflugia, where it 

 is pitcher-shaped, the animal pro- 

 truding itself from that part which 

 represents the mouth of the jug. 

 Many physiologists suppose that 



the Amoeba is not a perfect being, but it is merely the larval state of some animal with a higher 

 development, such as the Arcella and other shell-bearing Rhizopods. 



The genus Perinidium may be known by the furrow that runs transversely around the 

 body, and is furnished with cilia. The integument of the body is membranous. The Tripos 

 Perinidium is remarkable for its power of shining by night. It may be recognized by the 

 shelly case, which is concave, smooth, and is developed into three horns, two being long and 

 the other comparatively short. The longer horns are in front. Its length is about 150th of an 

 inch. The Kerona also belongs to this order, and is found in fresh water, where it may often 

 be seen in considerable numbers. Besides the usual cilia, it is furnished with instruments of 

 progression that enable it to climb and creep, and are formed like bristles or booklets. Its 

 length is rather variable, but is about equal to that of the Peridinium. 



AMCEBA Ani&ba \trineeps. 600 times enlarged, a and 6 enow the same animal in 

 changed form. 



INFUSORIA. 



E now come to the Infusoria, creatures which are all of very minute dimensions, 

 and respecting which there is great uncertainty prevailing. As with the pre- 

 ceding class, no definite system has yet been invented by which they can be 

 arranged ; and in many cases physiologists are undecided whether the tiny 

 beings are veritable species, or whether they are but the larval forms of higher 

 beings ; while, in some cases, it cannot be precisely ascertained whether they 

 belong to the animal or vegetable kingdom. 

 Without, therefore, occupying our space with disquisitions which would require a volume 



for their full elucidation, we will proceed at once to some of the more remarkable forms among 



these curious beings. 



Voi, HI.-74. 



