298 JULIAN §. HUXLEY 
into spherules. No gelatinous layer was seen round this mass. 
This was paralleled in the development of some other masses ; 
e.g. that shown in fig. 2, a, had, three days later, assumed the 
appearance shown in fig. 2, b. The smallest spherule was 
unchanged. ‘he remaining five, however, were all surrounded 
by a well-marked epithelium of dermal cells very different 
from the epithelium shown in fig. 1, which I take to be choano- 
cytic. The masses had swollen up by the secretion of fluid. 
The central portion had in three of the spherules begun to 
fragment. The gelatinous layers were of the same thickness 
as before. Although no cell-outlines had been visible in the 
spherules when examined three days previously, it had been 
noticeable that their outer boundary was very sharp. Other 
observations give colour to the idea that this sharp boundary 
heralds the formation of a dermal epithelium. 
In this case the dermal epithelium is formed after the 
spherules have been produced. In the mass shown in fig. 3, 
the whole mass forms a dermal epithelium, and the spherules 
are then produced internally. 
The further history of the spherules was as follows. The 
majority showed disintegration of the types shown in figs. 5 
and 6. A few degenerated directly. No recovery was observed 
in spite of change of water. This, however, may only mean 
that laboratory conditions were unfavourable. It is to be 
remarked that the general appearance of the tissues in stages 
like that of fig. 5 was perfectly healthy. 
Another culture was later found, where the same processes 
were observed. It was unfortunately not possible to carry 
out experiments to determine if subdivision could be initiated 
at will. 
The subdivision appears to be primarily a reaction to un- 
favourable conditions (witness the accumulation of bacteria 
round the edges of the subdivided masses). In all the dozens 
of dissociation cultures I have made at Naples, Wood’s Hole, 
and Plymouth, these two were the only ones where subdivision 
was observed. Both these cultures were from teased, not 
squeezed, material. 
