234 
PHARMACEUTICAL BOTANY 
small, sterile, vegetative cells that do not divide and from io to 12 
larger vegetative ones that divide to form new colonies. The latter 
slip inward below the level of the smaller cells and through repeated 
divisions form a number of ciliated cells jointed by cytoplasmic 
threads, which in reality is a minature colony. This then escapes to 
the exterior through the rupturing of the gelatinous wall of the old 
colony. 
During autumn of the year, certain of the ordinary cells undergo 
differentiation, some to form sperm cells, others, egg-cells. When 
about three times the size of the ordinary sterile cells, the sperm cells 
divide repeatedly to form a cluster of elongated secondary cells 
[Fig. 112 (1 a , a 2 and 5),] each of which contains an orange colored 
endochrome with a red corpuscle and an elongated beak, bearing a 
pair of flagella (lash-like processes). The cluster in time separates 
into motile antherozoids [Fig. 112 (6, 7)] which finally escape into 
the cavity of the volvox sphere through rupture of the investing 
wall. The flask-shaped egg cells (ib, b) increase greatly in size with¬ 
out dividing. Each shows vacuoles, then becomes filled with a 
dark green pigment, becomes spherical and acquires a gelatinous 
envelope. It then passes into the cavity of the sphere where it is 
surrounded by numerous antherozoids (3) and is finally fertilized. 
The product of this fertilization is an oospore (4) which ere long 
becomes covered with an internal smooth membrane and a thicker 
external spinose coat. The chlorophyll within then disappears and 
starch and a reddish- or orange-colored oil make their appearance. 
Up to 40 of these oospores have been observed in a single volvox 
sphere. Not long after the formation of these oospores the whole 
parent colony breaks up and the oospores fall to the bottom of the 
pool to pass the winter season. As early as February each oospore 
germinates to form another volvox colony, which repeats the life 
cycle described. 
3. Order Confervales. —In this order are included a variety of 
green filamentous and membranous forms some of which show sexual 
reproduction. 
Family Ulothricaceae. —Ulothrix zonala, a typical representative 
of this family, is a filamentous organism found growing on stones 
around ponds, on rocks along the shores of lakes, in slow-moving 
