. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 310 bulletin: museum of comparative zoology. would be one or two free broken ends for each piece, but one does not find it so. Occasionally a single free end may be found but scarcely ever two free ends on the one piece. In the case of the growing end of the stolon it appears that since there is no longer any inducement to continue in the same general direction in which growth has previously taken place, on account of the lack of support, the growth is completed by producing a zooid which thus terminates the stolon an
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 310 bulletin: museum of comparative zoology. would be one or two free broken ends for each piece, but one does not find it so. Occasionally a single free end may be found but scarcely ever two free ends on the one piece. In the case of the growing end of the stolon it appears that since there is no longer any inducement to continue in the same general direction in which growth has previously taken place, on account of the lack of support, the growth is completed by producing a zooid which thus terminates the stolon and leaves no free growing end. The lack of free broken ends seems bewildering at first and it seems per- missible to conclude that here is something new^ in hydroids, viz:— colonies developing from planulae at the surface of the high seas, for how could so many colonies, perfect ones at that, appear if they had been broken away from their regular support. Further examination. Fig. 74.— Clytia cylindrica. brings out the fact that regeneration is responsible for the deception, but conditions must be very favorable for such regeneration since in almost every instance a zooid is growing out from the broken end and all are in good condition. In many cases the regenerated portion is so nearly equal in size to the original part, both in the perisarc and in the coenosarc, that it is difficult to detect the junction and hence the deception is complete. In other cases the regenerated part is suffi- ciently smaller to be readily noticed. Besides the zooids that grow out from the broken ends, others appear to have developed in the regular way after the separation from the support, as, instead of coming off regularly in the one direction, they may come off on any side of the stolon to make the colony de- cidedly irregular (Fig. 73). Commonly when a straight piece of stolon regenerates, a zooid grows out from each end in line with the stolon itself, while the zooids previously attached we
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