ZOOPHYTES. 39 



before we find one whose stem and parts of the frond are 

 covered with a plantation of erect-growing "somethings," 

 that look like the backbones of some small fishes. They are 

 only about an inch in height, very 

 slender, and regularly notched on each 

 side. Some of the specimens have one 

 or two branches, but most of them are 

 simple erect stems. It is known as 

 the Sea Oak Coralline (Sertularia 

 pumild) , and if we examine it with our 

 lens, we shall find that each of the 

 notches represents the space between 

 the elegant crystal vases that are 

 arranged symmetrically along each 

 side of the stem. These vases are 



SEA OAK CORALLINE. , 7 j . i jv 



known as calydes, and m each there 



stands a polypite, reaching out its upper portion and waving 

 its tentacles. In case of danger the polypite can be withdrawn 

 into the calycle ; and certain species have an auto- 

 matic contrivance for closing the mouth of the vase 

 when they have retreated within. All genera have 

 not these calycles. 



Returning to the animal for a moment, it should 

 be explained that its organization is so low that 

 there is no true circulatory system for the renewal CALYCLES OP 

 of the body, by the carrying of elaborated food S ***E 

 from the stomach to distant parts of the body; 

 but by the activity of innumerable eye-lash-like hairs on the 

 surface the whole of the particles of food digested in the 

 stomach are carried all over the system to be then assimilated 

 by different parts. 



Within the circle of tentacles is the mouth, which is some- 

 times cut into lobes, and is generally borne upon a very mobile 

 proboscis, which may be withdrawn or protruded, and in some 

 genera takes a trumpet-shape ; in others it is conical. In the 

 winter the casnosarc may frequently be found with all its 



