SEA-MA T MAKERS. 299 



"the following points may be taken as established : 

 (i.) The brown body is universally derived from the 

 substance of the histolyzed polype. (2.) It is 

 always attached (when occupying its original position) 

 to the funiculus, and more or less invested by the 

 funicular plexus. (3.) Buds for the production of a 

 new polype are very commonly developed in the 

 closest proximity to it, and on its surface. (4.) They 

 also originate in various positions, and at greater or 

 less distances from the brown body. (5.) In some 

 species the latter is enveloped by the neighbouring 

 bud, and passes into the digestive canal, being ulti- 

 mately expelled through the intestine, either entire, 

 or after having undergone dissolution in the stomach. 

 (6.) There may be several brown bodies in a cell ; 

 and in some cases they lie loose in the perivisceral 

 cavity near the bottom of it." 1 Hence the final 

 issue has apparently still to be decided, and the con- 

 tradictory facts reconciled, that the same body may, 

 in some cases, be an important reproductive factor, 

 and at another ejected as mere rubbish. 



Singular appendages, called " birdVhead pro- 

 cesses," are found attached to the sides of the cells 

 in some species of the Sea-mats. Their functions are 

 very imperfectly known, but their appearance at- 

 tracted the attention of Darwin when on his voyage, 



1 Hincks, " British Polyzoa," vol. i. p. 63. 



