174 BOTANICAL GAZETTE [MARCH 
are homologous cannot be doubted, since: their origin and early 
development are identical in all details. The occasional appearance 
of sterile representatives of sexual organs within the cryptostoma 
further confirms this view of their relationship and strongly supports 
the theory of Bower (’80) that the cryptostoma in the Fucaceae is 
derived from the conceptacle. 
The occurrence of conceptacles in special reproductive branches 
only, the appearance of cryptostomata in both vegetative and repro- 
ductive branches, and the development of representatives of sexual 
organs within the cryptostomata, suggest a line of evolution from 
plants bearing conceptacles scattered over leaf and branch struc- 
tures indiscriminately, to the type now under consideration with 
localization of the conceptacle upon special branches. Certain 
branches were set apart to bear conceptacles as the conceptacles in all 
other parts of the plant body were rendered sterile and thus changed 
into cryptomostata. The presence of sexual organs or their degenerate 
representatives within a cryptostoma indicates, according to these 
views, that the process is not carried to its farthest point in Sargassum. 
The production of conceptacles upon small special branches only, 
instead of upon the entire plant, naturally results in fewer concep- 
tacles upon one plant. The conceptacles, however, are much more 
closely placed than the cryptostomata. On account of their com- 
paratively small size the initials and young conceptacles occupy very 
little space in the apex of a branch, but farther down on the receptacle 
the bulging bowls of the developing flask-shaped conceptacles require 
more and more space, until the mature structures nearly fill the 
interior of the receptacle and there is only enough intervening tissue 
to hold the conceptacles together. The cryptostomata, on the other 
hand, are well scattered upon vegetative branches and mature leaves. 
The contrast in the placement of cryptostomata with that of concep- 
tacles is, therefore, very marked. 
THE SPERMATOCYST. 
The male sexual organs (antheridia), which will be called sper- 
matocysts in this paper, according to the terminology of DAvis (:04), 
develop from wall cells of the conceptacle in Sargassum as in other 
forms of the Fucaceae. A wall cell puts forth a papilla (fig. 23) which 
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