550 ALFRED C. HADDON. 



It is impossible to regard the body-wall and the alimentary 

 canal of the Entoprocta as distinct individuals, and their 

 gemmation resembles, in its essentials, that of those animals 

 which can multiply by budding (e.g. Ascidians). The budding 

 of some of the Phylactolsemata, too, does not necessitate this 

 strange commensalism. Why, then, should it only occur 

 amongst the Gymnolsemata ? 



Let us admit that the previous inhabitant of a zooecium dies 

 away altogether, but before doing so gives rise to a bud in a 

 normal manner, which bud is primitively located on the oral 

 wall of the zooecium of its parent. The future history of the 

 bud would present no startling peculiarities if its growth were 

 to take place in two directions; if some of the epiblastic and 

 mesoblastic portions of the bud tended to form the body-wall 

 of the new Polyzoan : as it is already provided with an ectocyst 

 there would be no need to form a new one, so the new body- 

 wall would simply be applied to the dead cyst. Meanwhile, 

 an epiblastic involution depends into the body cavity of the 

 newly-formed individual, carrying down with it the hypoblastic 

 derivation from the parent, both being coated with a meso- 

 blastic sheath. This is the structure which has been regarded 

 by authors as a whole bud, and which has been variously termed 

 *' bud," " zooid," " polypide,'^ and " polyp,'' but which I make 

 bold to say is merely a portion of the new bud. (It will be 

 noticed that in the preceding pages I refer to this structure 

 under the generally received terminology, I purposely do so to 

 prevent any confusion.) I have already detailed the future 

 history of this part of the bud, so it would be superfluous 

 to repeat it again here, and that of the body-wall has no especial 

 interest. 



It might be objected that the funicular tissue extends through- 

 out the entire colony, and that it does not die with the tempo- 

 rary inhabitants of the zooecium; assuming this to be the case, 

 there is nothing to prevent this tissue being enclosed by the 

 body-wall of the growing bud, without its being a primitive 

 portion of that bud, after being thus enclosed it would serve 

 to connect the new member with the rest of the colony, and 



