126 BULLETIN OF THE 



formed by an invagination of the outer layer of the colony-wall, and 

 their outer layer from the inner layer of that wall. 



In Endoprocta, Seeliger ('90, pp. 176-187) has shown decisively that 

 the inner layer of the bud is derived solely from the ectoderm, and that 

 this inner layer gives rise to the digestive epithelium of the alimentary 

 tract, to the nervous tissue of the brain, and to the outer layer of the 

 tentacles. Here mesenchymatous cells, representing undoubtedly meso- 

 dermal tissue, come secondarily to surround the polypide as a loose 

 outer tissue. In Loxosoma the same is probably true. 



The conditions of budding in Gymnoloemata are more difficult to un- 

 derstand. In Paludicella the bud seems to arise as in Phylactolsemata 

 (Allman and Korotneff). The same is probably true for Alcyonidium 

 (Haddon, '83, p. 523, Plate XXXVIII. Fig. 23). In the Cheilostomata, 

 however, the fact of the great development of a loose mesenchyme-like 

 tissue obscures the process, and makes it difficult of interpretation. 

 This tissue, which is known under three probably homologous terms, — 

 " Funiculargewebe," Nitsche, "Parenchymgewebe " in part, Yigelius, 

 and " Endosarc," Joliet, — is to be considered as representing the funicu- 

 lar and ccelomic tissues of Phylactolsemata. The most careful observa- 

 tions on the origin of this tissue are those of Joliet ('77, pp. 249, 250, 

 and '86, pp. 39, 40) and Vigelius ('84, p. 76). Both authors assert 

 that this tissue is derived from cells given off from an epithelium at the 

 distal end of the budding individual. Vigelius ('84, pp. 19, 79) believes 

 that this epithelium is ectodermal, and that it is the sole rudiment of 

 this layer; but Ostroumoff ('S5 } p. 291) and Pergens ('89, p. 505) 

 have shown that the ectoderm persists and secretes in its cells the cal- 

 careous ectocyst. It seems more probable, however, that the "funicu- 

 lar tissue" arises from the inner layer of the body-wall (Nitsche, '71, 

 p. 37, Plate III. Fig. 5, c), and is the equivalent of the ccelomic epithe- 

 lium of Cristatella. The fact that many of these mesenchymatous cells 

 conglomerate in the formation of the polypide sufficiently accounts for 

 the origin of its outer layer of cells. The origin of the inner layer is 

 problematical, if, as is asserted to be the case by several authors, the 

 bud is not formed in the region of the body-wall. 



It will be premature to speculate upon the significance of the facts 

 of budding in the Ectoprocta until we shall have gained a more com- 

 plete knowledge of the ontogeny of the group, and of the relationship 

 of the Cheilostomatous to the Phylactohematous type through compara- 

 tive agamogenetic studies. It may appear in the end, that, under cer- 

 tain circumstances, undifferentiated embryonic tissue, derived from a 



