8 9 
Cutleria multifida ( Grev .). 
a distinct brown film. Germination, as already described by 
the brothers Crouan, took place immediately, and with 
considerable rapidity (Fig. i). As in the case of the 
oospheres of Cutleria , the zoospores came to rest, the anterior 
end became attached to the sides of the vessel or to another 
plant, and grew out into the first rhizoid. In the case of 
free-floating spores the rhizoid elongated considerably if it 
did not come into contact with anything, but ceased to 
elongate further on contact (Fig. 2). A simple filament 
of 3-6 cells was formed in a few days, and this agrees with 
the rate of germination observed for the oospheres of Cutleria 
grown at an approximately equal temperature. 
As growth proceeded, the film stretched over the surface 
of the water in the vessel, forming a pure culture of ger- 
minating spores, from which portions could be readily trans- 
ferred to other vessels of water similarly filtered by a 
Berkefeldt filter. Beyond keeping the vessels covered, to 
prevent evaporation and the entry of dust, no further change 
was made ; the best results, in fact, being obtained from the 
original culture in which the water remained unchanged for 
over a month. 
The filaments continued to elongate, by intercalary rather 
than apical growth, but the characteristic cessation of growth 
observed in the foot-embryo of Cutleria did not set in ; 
steady intercalary growth enabling the filaments to double 
their length each week (Figs. 5, 6). 
In the second or third week, differentiation in the cells of 
the filament became marked. The cells in the basal region 
of the plant increased in bulk and commenced segmenting 
irregularly by walls in different planes, thus rendering a lower 
region of the embryo multicellular by the same quadrant- 
walls, and at about the same age, as in the segmentation of 
the foot-embryo (Figs. 5-9). 
This basal multicellular region is therefore homologous 
with the foot itself, but the embryo differs in that the 
filamentous terminal portion goes on growing by a definite 
intercalary zone (Figs. 7- 10). 
