386 ETENINGS AT THE MICROSCOPE. 



irregular branches. The tips of these branches are 

 covered with a glutinous cement, by which thej 

 attach themselves tenaciously to glass, or other surface 

 near them. Having attached themselves, they expand 

 laterally, at the same time throwing out finger-like 

 prolongations, wdiich, as they come in contact with 

 each other, coalesce, until a fleshy plate is found 

 adherent to the glass. Polypes are developed both 

 from the loose branches and the attached polypary ; 

 and the latter is clearly seen to be permeated by a 

 beautiful system of anastomosing canals, connected 

 with the hollow bodies of the polypes. "Within these 

 canals may be detected an intermittent flow of fluid, 

 containing particles, the dancing motion of which 

 indicates the presence of ciliary action, and which, 

 having passed in one direction for a short time, are 

 arrested, and after a slight period of oscillation, com- 

 mence to flow in an opposite direction." 



The polypes which are developed from this living 

 carpet are not all of the same form. 'No fewer than 

 five distinct sorts exist, at one and the same time, and 

 I doubt not we shall be able to find and to identify 

 them all, on this well-grown specimen. 



First, there are the alimentary polypes, which we 

 have already cursorily glanced at. "Within the space 

 inclosed by the two circles of tentacles, there is a 

 mouth with soft protrusile lips, which can be pushed 

 out and folded back so as to hide tentacles, column, 

 s,nd all. 



Scattered amongst these we see numerous polypes, 

 which agree in general form with these, but with some 

 remarkable abstractions and additions. They have no 

 mouth nor stomach, and the tentacles are reduced to 



