320 THALLOPHYTES 
Kelps that much potassium for fertilizers is obtained (Fig. 275). 
Although the Kelps have massive and complex plant bodies, 
their reproduction, so far as known, is not so complete as that of 
some Green Algae. Their reproduction is sexual and the small 
ciliated gametes are borne in special cells which occur in patches 
Fic. 275.— Harvesting Kelp on the Pacific Coast. From Report 100, 
U.S. Dept. of Agriculture. 
on the surfaces of the leaf-like branches. The zygospore develops 
a new plant directly. 
Ectocarpus. — This form (Fig. 276), although belonging to the 
same order, contrasts strikingly in size with the Kelps, for it is a 
slender filamentous form not much larger than some of the Green 
Algae. This form also shows some interesting features in connec- 
tion with reproduction which is effected through the production 
of both zoéspores and gametes. 
The zoéspores are produced in certain cells which become trans- 
formed into sporangia. In forming a sporangium, a single cell 
within the filament or at the end of a branch usually enlarges 
and its protoplasm divides up into zodspores. The zodspores 
bear their cilia laterally and not terminally as in the Green 
Algae, but function in the same way by growing directly into 
new plants. 
