436 BOTANICAL GAZETTE [DECEMBER 
Suborder EcTOCARPINEAE.—Morphological alternation of similar 
generations shown or inferred to be present. 
Family 1. Ectocarpaceae.—Reproductive organs formed by 
the metamorphosis of all or part of a branch; growth of the free 
filaments intercalary. This is the primitive family of the class. In 
Ectocarpus the fusion of the elements from the plurilocular sporangia 
as gametes has been known since the work of BERTHOLD. Recently 
Kyutn (10) has reviewed the work on Ectocarpus, and contributed 
a study of two species, E. siliculosus and E. tomentosus. It is to be 
considered that the plants with sporangia (unilocular) and those 
with gametangia (plurilocular) normally alternate in the life cycle. 
Cases of abbreviation of this are well known, and peculiar conditions, 
as in E. Padinae Sauv., have been reported (33). The thallus is 
always primitively branching-filamentous, and intercalary growth 
is typical, but this becomes localized in some species into definite 
regions, while the hapteron branches and other attached or endo- ~ 
phytic parts grow apically. These features are of importance as 
indicating the source of similar characters in the following families. 
Family 2. Ttlopteridaceae-—Reproductive elements of two 
kinds, small motile cells which may function as isogametes, and 
larger non-motile cells often with more than one nucleus. These 
latter cells are of two kinds according to some accounts, represent- 
ing eggs without a membrane and but one nucleus, and mono- 
spores with a membrane and usually four nuclei. The oogamous 
character of this family has long been tentatively accepted, but 
has never been proved absolutely. On the basis of vegetative 
characters and an assumed isogamy, this family would stand in 
close relationship to the Ectocarpaceae, but if oogamy is actually 
present it would need to be placed in the Cyclosporales as a sub- 
order Tilopteridineae preceding the Dictyotinieae, differentiated 
by the thallus characters and the incomplete division of the spores. 
For a discussion of literature see KYLIN (9). 
Family 3. Sphacelariaceae.—Reproductive elements formed by 
the metamorphosis of all or part of a branch, growth from an apical 
cell. The originally monosiphonous filament usually divides up 
by internal walls, and may develop a peripheral meristematic zone 
producing a very considerable increase in thickness. Special vege- 
