108 The Philippine J ournal of Science 1922 
the gonidia of the daughters before birth are about equal in 
size in the same daughter. This probably holds true mainly in 
cases in which the gonidia occur in the typical number, eight. 
The number of somatic cells in the coenobia was not stated 
by Powers. Estimates of the number of cells in the coenobia 
shown in ten of his figures, based on counts of cells in small, 
centrally located areas,® with no allowance for the error due to 
the flattening of the coenobia for photography, give numbers 
ranging from 2,500 to 7,500, numbers coming between the 11th 
and 18th powers of 2, in which class the real numbers probably 
belong. Powers did not describe the somatic cells. His figures 
show the distance between the protoplasts to be greatest at the 
anterior pole and to diminish progressively toward the posterior 
pole, where it is least, the ratio of the intercellular distances 
at the opposite poles being, for example, in a nearly mature 
asexual coenobium (his fig. 46) nearly 2 to 1. 
The number of gonidia (which Powers erroneously called ova, 
occasionally referring to them as primary sex cells) in the 
asexual coenobia he stated to be, most commonly, eight and 
ten, the latter number predominating. Less frequently, he 
stated, there are twelve. Odd numbers also occur. 
The gonidia are differentiated from the somatogenic cells at 
about the 64-celled stage of the embryonic development; or, if 
not, certainly at the next step. They are large globular cells, 
which attain diameters of about 25 » before birth (his fig. 87), 
and as great as 90 » before segmentation (Powers, ’08, p. 156), 
the largest that was figured (his fig. 41) being about 65 p in 
diameter. They appear to be multivacuolate with a central 
nucleus. 
_ The arrangement of the gonidia is almost mathematically 
regular. When the number is eight the arrangement is simplest 
and symmetrical; four lie equidistant from one another near 
* The estimates were made by applying the formula, N= pt in which 
N is the total number of peripheral cells, D the diameter of the coenobium 
in microns, n the number of cells counted in a selected area, and c a. 
constant, representing 4 in the formula, N— 7m a batt 9 in which a is 
a 
T 
the area used for the counts. In this case the constant, ¢, was given a 
value of 1,000 by taking an area of 3,141 square microns. The radius of a 
circle having this area, multiplied by 79, the indicated linear magnification 
of the figures, was used for cutting a hole in a card which was placed over 
the figures for the counts. The diameter of that hole was about 5 milli- 
meters. 
