412 



they form a coral-like branching mass. Qn magnifying these cells 

 when the animal is alive and extended from its cell, each polypide, 

 as it is called, appears with its crown of tentacles somewhat like a 

 Sabellid worm. This crown of tentacles surrounds the mouth, 

 which leads by an oesophagus into the throat and a stomach, the 

 latter bent so that the intestine beyond ends very near the mouth ; 

 the polypide is thus bent on itself within the cell (cystid) and its 

 body is drawn in and out by muscles. Attached to the end of the 

 fold of the stomach is a cord (funiculus) holding the ovary in 

 place, which extends back to the end of the cystid, as we may 

 call the cell. 



Allman regards the polypide and cystid as separate individuals. 

 Now in confirmation of this view we have the singular genus Lox- 

 osoma, which is like the polypide of an ordinary Polyzoan, but 

 does not live in a cell. On the other hand, we know of no cystids 



The affinities of the Polyzoa to the worms are quite decided. 

 In the Phoronis worm, which is allied to Sipunculus, we have the 

 alimentary canal flexed, and the anus situated near the mouth. 

 The Polyzoa have but a single pair of nerve ganglia, and in some 

 cases a tubular heart. The fresh water species are the higher, 

 and are called Phylactolaemata ; the marine species are termed 

 Gyiniiol.emata. All the Polyzoa are hermaphrodite, the ovaries 

 and male glands residing in the same cystid. 



Development of the Polyzoa.— Kemembering that the cystids 

 stand in the same relation to the polypides as the hydroids to the 

 medusae, as Nitsche insists, we may regard the polypides as sec- 

 ondary individuals, produced by budding from the cystids. The 

 large masses of cells forming the moss animal, which is thus a 

 compound animal, like a coral stock, arises by budding out from a 

 primary cell. The budding process begins in the endocyst, or 

 inner of the double walls of the body of the cystid, according to 

 Nitsche, but according to an earlier Swedish observer, F. A. Smitt, 



!■■■'!;. : : i in.' cystid. 



Nitsche has observed the life history of Flustra membranacea. 

 He has traced the budding of one cell or zocecium (representing 

 the cystid individual) from another. During this process the poly- 

 pide within decays, leaving as a remnant the so-called "brown 

 body," regarded by Smitt as a secretion of the endocy st and u * m 

 of a new polypide. After the loss of its first polypide, it can pro- 



