162 BROOKLYN BOTANIC GARDEN MEMOIRS 
(13) has obtained in his very interesting and suggestive experiment 
with paraffine wax cooling over mercury, a configuration determined 
entirely by the molecular forces operating in the system. It would 
be possible to form a sphere out of these nineteen units, but there is 
nothing in their number to favor the change from the discoid to the 
spherical grouping. To make a hollow or solid sphere out of such a 
group would involve very fundamental rearrangements. 
On the other hand, if we make a diagram of the arrangement of 
the sixteen cells produced by binary fission, assuming for the sake of 
simplicity that each pair of daughter cells instead of remaining flattened 
upon each other with the resulting lateral displacement (Klein, Taf. 
VI, Figs. 61-63) rounds up completely after the third division and 
that the four cells first formed remain fixed by adhesion, we get the 
3 4 
Fics. 3 and 4. For explanation see text. 
configuration shown in text-figure 3. Here it is obvious that as con- 
trasted with the arrangement in text-figure 4 it is a simple matter for 
the group to become cup-shaped and spherical simply by folding in 
the radial series and that the four outermost cells will come together 
ina group of four with its members alternating with those of the 
original group of four. 
The group produced by binary fission in two planes with elongation 
of the cells upon their free surfaces and strong adhesion tends naturally, 
especially in the cavity of a spherical mother cell, to produce a globular 
young colony at the sixteen-celled stage. 
As noted, all authors agree in maintaining that all the cells of the 
colony divide up to the sixteen-cell stage when the spherical form is 
practically complete. The later stages have not been followed. 
