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F. E. Fritsch. 
chloroplast and eye-spot. Moreover the Phaeophyceae are essen¬ 
tially marine. If we look at Schenck’s work from the point of 
view of parallel development, however, it is exceedingly instructive. 
A detailed discussion is unfortunately impossible. 
Before dealing with the established cases of alternation among 
the Brown Algae, it will be well to examine a little more closely the 
lowest series of this group, viz., the Ectocarpales. This may 
probably be regarded as displaying many of the more primitive 
characteristics of the Phaeophyceae, and in many respects affords an 
astonishing degree of parallel with the Chaetophorales. The simple 
filamentous Ectocarpus has a thallus differentiated into the same 
two portions as a Myxonema, i.e., there is a creeping base and an 
upright system, the branches of the latter often terminating in hairs. 
There are a large number of forms (Ascocyclus, Fig. 2, d, etc.) in 
Fio. 2. a, Myrionema vulgare, showing zoosporangia and gametangia (g) 
(after Sauvageau) ; b, young Aglaozonia -thallus (from Oltmanns) ; c, abnormal 
Cutleria (from Oltmanns) ; d, Ascocyclus secundus, a young thallus (after Reinke). 
