44 BRYOZOA ECTOPROCTA. 



of the brown body. A certain difficulty attends this assumption, in consequence 

 of the development of the intestine in the young buds, in which there is no 

 brown body. OSTROUMOFF, however, tries to escape these difficulties by 

 pointing out the relations established by the funicular tissue between the 

 parent-zooecium and the bud, as well as by assuming that in this way ento- 

 dermal cell -masses pass from the parent into the bud. In this respect the 

 views of OSTROUMOFF have something in common with those of HADDON, 

 who held that all the three germ-layers of the parent-zooecium took part in 

 the formation of the bud. According to JOLIET (No. 17), the alimentary canal 

 of the developing polypide does not originate from the inner layer of the 

 bilaminar sac-like polypide-rudiment, but from a distinct cell-mass derived from 

 the outer layer of that rudiment. The inner layer of the polypide-rudiment 

 would then yield only the ectodermal parts of the polypide, while the outer layer 

 would contain the mesodermal and entodermal parts. In any case, according 

 to JOLIET, the enteric canal (mid-gut) has an origin distinct from that of the 

 ectodermal rudiment. The most recent researches, however, confirm the view 

 that the whole intestine of the polypide originates from the inner layer of the 

 double-walled sac, i.e., from the ectoderm, but PROUHO differs to some extent 

 from the description given above and founded on the statements of more recent 

 authors, for he regards a small mass of irregularly-arranged cells, lying at the 

 end of the diverticulum d in Fig. 20, as the rudiment of the mid-gut, while the 

 hind-gut arises exclusively from the diverticulum itself. According to PROUHO, 

 indeed, this cell-mass is to be derived from this same diverticulum ; but it 

 cannot be denied that this statement is likely to strengthen the doubt that has 

 long been felt as to the common origin of the fore-, mid-, and hind-guts. 



V. Asexual Reproduction of the Ectoprocta. 

 A. Budding. 



In the Bryozoa, the colonies are produced by the continuous 

 budding of the primary individual. The nature of this budding 

 has been carefully studied by NITSCHE (Nos. 23 and 52), and more 

 recently by BRAEM (No. 45a) and DAVENPORT (^N T os. 11 and 46a).- >; 

 Two kinds of buds may usually be distinguished, according to 

 the direction of their growth : (1) those that continue to grow in 

 the same direction as the parent-zooecium, such buds serving for the 

 direct prolongation of the branch or branchlet to which the parent- 

 zooid belongs; and (2) those that, in growing out from the 

 parent-zooecium, take a new direction and thus give rise to new 

 branches. In many cases the new branches grow out laterally. 

 The buds of the second kind are then lateral buds, while the mediaii 

 buds provide for the continuation of the branches, such individuals 

 usually continuing in the same axial direction as the parent. It 

 should, however, be mentioned, that in many cases median buds 

 may also give rise to new branches, since, while retaining the same 

 plane as the mother, they may take a new direction. 



* [For the development of the colony in the Gynmolaemata, see important 

 papers by HARMER on Lichenopora, Crisia, and Tubulipora. Quart. Journ. 

 Micro. Sci., Vols. xxix., xxxii., and xli. ED.] 



