BUDS OF CEPHALODISCUS HODGSONI. 61 



when nearly of full size, separates from the parent by severance at the distal end of 

 its stalk from the end of the parent stolon, and is now in the position of the parent 

 individual referred to in the beginning of this paragraph. Sometimes tlie parting 

 from the parent individual is delayed until the seceding bud has developed a second 

 bud of its own. 



What happens to the parent polypide when its two buds have departed can 

 hardly be determined except by tracing the process of budding in a living colony. 

 Possibly it produces young buds at the same rate as the old buds separate off, so 

 that the number of buds on the parent stolon is maintained at two. If this be so, 

 there is less reason for doubting that a in fig. 84 is the parent stolon, and / its 

 recently formed bud. 



What are the conditions which determine whether or no a parent stolon or a 

 bud-stalk shall constrict and divide at its middle, or at its proximal end, are 

 difficult to conceive. The acceptance of Harmer's view that the individuals so 

 liberated are " degenerated " is hardly possible in view of the healthy appearance 

 of the polypides shown in figs. 80 and 82 ; yet what became of the stolon- 

 less polypides and stalkless buds after their separation liy this method is a 

 mystery, for no such individuals have been encountered in the course of the 

 investigation. Since in the whole animal kingdom it is so very unusual for 

 sexual reproduction and vegetative reproduction to take place simultaneously 

 in the same body, may one conjecture that sexually reproducing polypides first 

 cast off their vegetatively produced families, together with the gemmation-tissue 

 of the stolon, and become more free-living in their habits, perhaps leaving the 

 colony altogether ? This explanation would account for the absence of stolonless 

 polypides in the mass of individuals taken from the cavities of the tubarium. 



That the constriction and division of parent stolons and bud-stalks is due to 

 the convulsive contraction of certain parts of the concentric muscles at the time 

 of death, is rather negatived by the perfect rounding off of the free ends of the 

 sausage-like structures, and by the absence of stolonless polypides in the material 

 examined. Further than this, in C. nigrescens, the sausage-shaped piece of stalk 

 is sometimes found with buds at its free end as well as at its basal end (figs. 69, 

 71 and 73). 



Buds. 



The bud on its first appearance is ellipsoidal or ovoidal in shape (fig. 54, plate 6). 

 The attached end becomes narrower, and the free end becomes flattened dorso- 

 ventrally into what will later be the anterior part of the buccal shield. The 

 posterior edge of the buccal shield next becomes marked out by the appearance of 

 a curved groove, situated about halfway along the ventral surface of the bud, and, 

 at the same time, the first pair (jf plume-axes develop as hemispherical swellings 

 on the dorsal surface (fig. 55). The l)uccal shield enlarges in all directions, and 



