HISTOLOGY AND DEVELOPMENT OF MYRIOTHELA PHRYGTA. 513 



endoderm are undistinguishable. This grows while at the 

 same time its elements lose their distinctness and become 

 highly charged with spherical masses of stored nutriment, 

 resembling in many particulars the nutritive spheres of the 

 general endoderm. As it grows it pushes the perisarc before 

 it, and ultimately forms a rounded egg-like mass attached to 

 the parent body by a short thick pedicle (fig. 13). From 

 this the young Myriothela is developed (fig. 13). All con- 

 nection with the body of the parent is lost at a very early 

 period, almost before the bud has re-formed its ectoderm and 

 endoderm and enteric cavity. It remains attached to the 

 perisarc, however, by a sucker -like arrangement at the aboral 

 pole until it is fully formed. 



As will be seen, the formation of a gonophore is, in its 

 earliest stages, essentially similar to this method of budding. 

 In other words, the gonophore is a true bud which, like the 

 other buds, is derived from a blastema formed by a fusion of 

 ectodermal and endoderraal elements. The difference, however, 

 lies in the fact that in the case of the gonophore bud, after it 

 is a well-formed structure, a group of the primitive germ-cells 

 make their way into it. 



The first stage in the growth of a gonophore is shown 

 in fig. 8. The ectoderm of the gonophore-bearing region 

 becomes thickened over a small surface, the increase in 

 thickness being due largely to an accumulation of the 

 primitive germ-cells, but partly to an increase in the cells 

 carrying hyaline masses. At the same time nematocysts dis- 

 appear in that region of the ectoderm, though they may occur 

 in their usual profusion in close proximity. In the next stage 

 the basement membrane is absorbed or ruptured (figs. 7 and 

 9), I cannot determine which, and a tongue of endoderm- 

 cells pushes its way into the ectoderm and through the deepest 

 layer. Thus the cluster of primitive germ-cells come to lie 

 not on its apex, but, generally, asymmetrically disposed on 

 one side. 



The removal of the supporting lamella is, I am inclined to 

 think, mainly a process of solution, since scattered rounded 



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