24 Coelenterata. 



normal fashion. The budding does not depend on the attainment by the 

 parent-stock of a certain size-limit, but on that of a definite ontogenetic stage. 

 7 planulse (of 128 or more cells) were cut into pieces which soon rounded 

 themselves off and continued their development for a time apparently unimpaired. 

 In this way several swimming planulse, in one case 9, were obtained from a 

 single egg. Of the 31 fragments obtained only 2 developed into normal dwarf 

 colonies, all the others produced abnormal or defective larvae, the most ab- 

 normal arising from the smallest pieces. At this period the power of regu- 

 lation seems to be already diminished. When the peduncle of a young colony 

 is removed at any level a new one is soon formed ; removal of the axial polyp 

 by transverse section leads to the regeneration of that polyp; a severed 

 peduncle did not regenerate a new axial polyp at its anterior end; by oblique 

 section through the budding zone two colonies may be produced from one. In 

 one case reversal of polarity was obtained [cf. Bericht f. 1901 Coel. p 16 

 Torrey]. A colony was cut into 3 pieces, the peduncle failed to survive 

 as usual, the middle piece regenerated an axial polyp in front and a peduncle 

 behind, the anterior piece regenerated a large polyp at the posterior end thus 

 producing a specimen with 2 similar polyps connected by their bases and 

 pointing in opposite directions. Each had a stomodseum, the mesenteries were 

 continuous from one to another and there were 6 mesenterial filaments. The 

 original tentacles of the axial polyp lost their pinnules , became greatly shor- 

 tened and formed processes similar to those of the regenerated polyp. Regene- 

 ration takes place at the cost of the whole organism often involving regressive 

 changes in parts already formed. The above case shows reversal of polarity 

 and proves that regeneration may take place anterior to the budding zone. 

 A peduncle was removed by section posterior, but quite near, to the budding 

 zone, a new axial polyp was formed at the anterior end of the peduncle and 

 a pair of buds appeared. Colonies were cut so as to leave a single small bud 

 attached to the peduncle. As this bud is destined to develop into a polyp 

 like the axial one it might have been expected that it would develop at once 

 into a new axial polyp but it remains stationary, or may even be resorbed, 

 while a new axial polyp is regenerated at the anterior end of the peduncle, 

 then a second bud appears on the other side. This stage appears to be a 

 definite ontogenetic stage which represents a condition of equilibrium first re- 

 stored after operation before further growth takes place. There seems to be 

 a definite morphological relation between the members of a colony. In 

 colonies cut into two at an angle of 45 so as to leave one of the primary 

 lateral buds in each piece a plastic remoulding quickly occurred so that by 

 mechanical means, without the formation of new tissue, the lateral bud of 

 each piece became displaced, in the posterior piece so as to project straight 

 forward giving the appearance of an axial polyp and in the anterior piece 

 projecting straight backwards. In 48 hours a rapid formation of new tissue 

 took place in both pieces, in the anterior piece a new peduncle, and in the 

 posterior one a new axial polyp being produced, and the lateral buds were 

 soon swung back to their original positions. 



Bourne (^ describes the branching systems of Alcyonacea in general and of 

 Lemnalia in particular. In L. the upper part of the stomodseum is swollen 

 and lined by a tall columnar epithelium containing gland cells but no nemato- 

 cysts. There is no groove in this part but towards its lower end where the 

 storn. narrows the cells lining the ventral wall become elongated and each 

 bears a single long ciliuni. This modified strip forms a shallow groove, but 

 lower down the stom. is compressed laterally and lined throughout by a modified 



