166 SIDNEY F. HAEMER. 



bud is itself mature. It is worthy of remark that the young 

 vestibular invagination does not occur accurately at the apex 

 of the stolon, but on the side of the apex turned towards the 

 growing point. In this respect it exactly agrees with the 

 position of the vestibular invagination formed near the apex 

 of a stalk which has lost its calyx, and again with that of the 

 incompletely rotated vestibule in intermediate stages of the 

 metamorphosis. It may indeed be said that the young 

 vestibule of all the buds is inclined towards the growing point, 

 and that in all cases it subsequently undergoes a rotation in 

 the same direction (but to a less marked degree) as that occur- 

 ing at the metamorphosis. 



The history of the Pedicellina-larva appears to me to point 

 to the existence of a fixation-period in Loxosoma also. In 

 this case, the buds observed by me in the larva of L. Lepto- 

 clini would probably have to undergo a change of position, 

 during the metamorphosis, similar to that represented in figs. 

 17 — 19. I am inclined to believe that the degeneration of the 

 larval stomach observed in the same species, after a free life of 

 one or two days, was abnormal, and was due to the absence of 

 the conditions necessary for fixation. 



On the Nature of the "Brown Bodies" of the 

 Ectoprocta. 



The above statements with regard to the life-history of the 

 Entoprocta may, perhaps, give some indication of the manner 

 in which the "brown bodies" of the Ectoprocta have origi- 

 nated. There can probably be no longer any doubt whatever 

 that these structures are degenerated polypides, which are 

 subsequently replaced by new ones budded ofi' from the walls 

 of the zcoecia. 



In the metamorphosis of Pedicellina the purely larval 

 organs degenerate and form a mass of cells, which subsequently 

 become connective-tissue cells. The degeneration is here 

 slight, and has not yet acquired sufficient importance to give 

 rise to a characteristic " brown body." 



