302 
SIDNEY F. HARMER. 
which have just become free occur two very conspicuous lateral 
masses of large cells (figs. 50 and 51, hst.) lying between the 
epiblast and the stomach, and corresponding to those which 
seem to be originating in fig. 56. In larvae which have been 
free two days, the lumen of the stomach is almost completely 
atrophied (fig. 58, st.), although the oesophagus and intestine 
are much less altered. The figure represents the oesophagus at 
the point where it passes into the stomach, whose “ liver-cells” 
are still recognisable (/.). At the sides of the stomach are two 
masses of cells, probably corresponding to those developing 
in fig. 56 ; that of the left side is seen to pass to the base of 
the bud, whose outer portion is just involved by the section. 
In the other sections passing through the same larva, no stomach 
lumen could be discovered, but only a mass of cells (repre- 
sented in fig. 59), which fill up the whole of the central portions 
of the larva, and which pass to the bases of the bud. These 
appearances, which are not confined to a single larva, have led 
me to form the following hypothesis of the budding processes, 
in default of a complete series of actual observations. 
One of the earliest formed parts of the bud is the epiblastic 
thickening, which occurs long before the embryo is ready to 
become free, and during embryonic life consists of a small 
number of large granular cells. Almost at the same time are 
proliferated off from the sides of the stomach a pair of lateral 
wings of hypoblast cells, destined to take part in the budding. 
After the commencement of the free life these cells increase in 
number by subdivision, new ones being at the same time 
formed from the walls of the stomach, which atrophies coinci- 
dently with their formation. The stomach is thus completely 
lost, and is replaced by a large mass of cells filling up the centre 
of the larva. The epiblastic thickening meanwhile has grown 
inwards, and the bud forms a projecting rounded lobe of the 
body of the larva. The epiblastic portion forms the lopho- 
phore and vestibule, the latter originating as a longitudinal 
slit, just as in the buds formed on the adult. The central mass 
of hypoblast cells is employed mainly as a food material 
during the development of the bud, but some of these cells 
