STRUCTURE AND DEVELOPMENT OF LOXOSOMA. 
303 
apply themselves to the deep end of the lophophore, and give 
rise to the stomach of the adult. I have one preparation of a 
larval bud, which seems to show this application of a hypoblast 
cell to the end of the lophophore. 
The origin of the various organs in the buds developed on 
the adult has been a subject of much controversy. The bud 
commences as an ectodermic thickening, growing inwards to 
form the lophophore. It is very difficult to determine satis- 
factorily whether the endoderm develops from cells proliferated 
from the stomach or from the ectodermic thickening which 
occurs at the apex of the bud. According to most observers 
the latter is the case. Although at present I have been unable 
to satisfy myself on this point, it has seemed to me, on the 
whole, probable that in the adult the stomach does give rise to 
cells, which apply themselves to the end of the lophophore, and 
are destined to form the stomach of the bud. I have been 
unable to convince myself of the accuracy of Haddon’s account 
(37), according to which the stomach at its earliest appearance 
is quite distinct from the lophophore. My own sections lead 
me to believe that the stomach is connected with the lopho- 
phore, even in its youngest condition, and that the only method 
by which it can have an endodermic origin is by the prolifera- 
tion of cells from the stomach, and by the application of these 
cells to the ectodermic part of the bud. The ectoderm and 
endoderm on this hypothesis become indistinguishable, so that 
at a later stage the stomach appears to be developed from part 
of the ectodermic thickening forming the lophophore. 
The most noteworthy features of the history of the larva to 
which it is necessary to call attention are (i) the fact that the 
dorsal organ takes no part in the budding, and (ii) the atrophy 
of the stomach after the commencement of the free larval 
existence. The latter fact probably indicates that the larva 
never becomes adult, but that it dies after the production of 
its buds. Although it is organised on a plan fundamentally 
similar to that of the adult there is still a very well-marked 
distinction between the anatomy of these two forms, and in the 
four days during which I succeeded in keeping some of my 
