Some Aspects of the At gee. 37 
have some real genetic relationship with the Ascomycetes, or with 
the Laboulbeniacete. This is the kind of suggestion of affinity, 
however, of which we have an instinctive distrust in the absence of 
the strongest evidence in the way of intermediate forms, and we 
hold it far more likely that the whole phenomenon is one of those 
elaborate pieces of parallelism in which the organic world is so rich. 
In any case the Florideae-Ascomycete hypothesis does not contribute 
towards the solution of the problem of the origin of the Red Sea¬ 
weeds. The true affinities of the Florideae must, we think, still 
remain a profound mystery. 
Professor Oltmanns leans strongly to the view of a separate 
flagellate origin for the Brown Seaweeds, on the ground of the 
specially characterised swarmer. Among the simple brown forms, 
however, which Scherffel put together to form a series, leading from 
the Flagellata to the Phaeophyceae, only Phceocystis has a swarmer 
of true Phaeophycean type, so that while we consider the separate 
origin of the Phaeophyceae an extremely plausible hypothesis, 
we must admit, as Professor Oltmanns says, that we do not know 
from what existing Flagellates they could have been derived. 
The treatment of the internal phylogeny of the Brown Sea¬ 
weeds is, we think, one of the mest satisfactory parts of this section 
of the work. The degree of sexuality will clearly not do as a primary 
principle of division; we must adhere to the structure of the 
thallus for this purpose. The Ectocarpaceae are taken in a much 
wider sense than usual, and from this great primitive group, the 
Laminariaceae are derived through Chorda , the Asperococcaceae 
through Myriotrichnm , the Mesogloeo-Chordarian series, as Professor 
Oltmanns calls it, and the Cutleriaceae on another side, and finally 
the Sphacelariaceae and Tilopteridaceae along parallel lines. The 
disc-forming types are in all cases considered as reduced forms. 
The details of this, to our mind very luminous, arrangement, are 
to be found in the Special Part (pp. 348 et seq.) of the work. The 
Dictyotaceae, on the ground of the general characters of the cell, 
and on the basis of Lloyd Williams’ discovery of motile anthero- 
zoids, are very rightly united with Fucaceae as Cyclosporeae, the 
existence of the so-called tetraspores being quite insufficient to link 
them with the Florideae. While it is not difficult to homologise 
the sexual organs of Cyclosporeae with the plurilocular sporangia of 
Phaeosporeae, it is not easy to say from which group of the latter the 
former have been derived. 
In the second chapter of the work a general account is given of 
