512 W. B. HARDY. 



powers, to be entirely free ; and these are the elements which 

 occur so characteristically in little groups, the cells of which so 

 frequently betray signs of active proliferation. These histo- 

 logical facts, together with the absence of these free cells in 

 other parts of the body and their peculiar relation to the gono- 

 phores, entitle us, I think, to regard them as preformed sexual 

 elements. 



The Earliest Stages in the Formation of the Gono- 

 phore and its Relation to the Process of Budding 

 in Myriothela. 



In early spring, and before sexual reproduction has taken 

 place to any marked extent, specimens of Myriothela may be 

 found which bear buds in various stages (PI. XXXVII, fig. 13). 

 These appear to be always developed just at the junction of 

 stolon and body. Once only have I met with a bud formed 

 elsewhere, namely, in the lower tentacular region. This had, 

 however, more the appearance of a permanent growth than of 

 a bud to be cast off. 



The process of budding, so far as I have followed it, is a 

 rather remarkable one. The first stage is a modification of 

 the character of the ectoderm, which in the stolon and lower 

 part of the body is composed of very long columnar cells, re- 

 sembling the columnar cells of the blastostylar ectoderm in all 

 particulars save in their inordinate length. Lying between 

 the bases of these columnar cells are interstitial cells, charac- 

 terised by the fact that they stain more deeply with picro- 

 carmine. These cells appear to be partly nervous and partly 

 concerned in the formation of nematocysts, which, curiously 

 enough, are produced in limited number even under the thick 

 and dense perisarc of the upper part of the foot. Where a 

 bud is about to be formed the ectoderm-cells lose their 

 defined characters, proliferate, and a bulging mass of amor- 

 phous tissue results. At the same time the thick supporting 

 lamella becomes absorbed, and the endoderm-cells likewise 

 proliferate and take on an amorphous character. The result 

 is a kind of blastema in which the limits of ectoderm and 



