122 
Flagellata and Primitive Alga. 
The position of Phceosphcera West is also doubtful, as the motile 
cells have apparently not yet been observed ; the same is the case 
with Stichoglcea and Gleothamnion, which would be included in the 
Phaeocapsacese if their motile cells were found to show Cryptomonad 
characters. Ncegeliella is epiphytic and forms multicellular discs, 
the individual cells producing a perisarc prolonged into a bristle; 
the motile cells have a single brown chromatophore and two 
laterally inserted flagella. The genus Phceothamnion appears to 
represent the highest form of the Phaeocapsacese, while Pleurocladia 
leads directly to the Ectocarpaceae and is placed in that group by 
Kjellman and Svedelius (66). A useful bibliography of the genus 
Phceothamnion is given by M’Keever (91), who recently discovered 
P. confervicolum (the only species known) in Scotland—it was 
previously recorded only from Sweden, Germany and Italy. There 
appears to be some doubt as to the insertion of the flagella and the 
nature of the motile cells ; according to Lagerheim the latter are 
zoogonidia with terminal flagella and no eye-spot, while Borzi 
described the conjugation of isogamous gametes with lateral 
flagella and a red stigma. Oltmanns (95) places Phceothamnion , 
with the other genera here regarded as forming the family 
Phaeocapsaceae, among the Chrysomonadinete. This genus is, 
however, apparently related very closely to Pleurocladia, which 
has the typical gonidangia and gametangia of the Ectocarpaceae. 
Bohlin’s genus Phceodactylon (9) cannot be included in the Phaeo¬ 
capsaceae, but is probably a Chrysornonad in which adaptation to 
plankton conditions has resulted in loss of the flagella ; its curious 
three-armed cell recalls the tetrahedal motile cells of Hydrurus. 
The greatest difficulty in the way of deriving the Phaeophyceae 
from the Brown Flagellates has been the characteristic lateral 
insertion of the flagella in the motile cells of the Brown Algae— 
excepting in the Dictyotaceae, which are somewhat isolated 
among the Phaeophyceaae. This difficulty has, however, been over¬ 
come by the discovery of Protochrysis, in which the furrow from 
which the flagella arise, instead of being longitudinal and subapical 
as in other Cryptomonads, is transverse, so that the flagella arise 
from the middle of the body, one flagellum being directed forwards 
and the other backwards. Protochrysis appears to stand very near 
the ancestral type which gave rise to the lower Phaeophyce® 
or to the series of transitional forms (Phaeocapsaceae) leading 
through Phaeothamnion and Pleurocladia to the Ectocarpaceae. 
The work of Pascher and Scherffel supports Klebs’ view that 
the Cryptomonads have arisen from the Chrysomonads and have 
no direct relationships with any other Flagellate group excepting 
possibly the Dinoflagellata (Peridiniales). Pascher, as we have 
already seen, merges the Cryptomonads in the order Chrysomonad- 
inere, and has shown that the organisation of a pulsating vacuole 
system, previously regarded as found only in the Chloromonads 
and the Euglenineae, occurs not only in the Cryptomonads but also 
among the Chrysornonad groups. Another distinction made by 
previous writers between the Cryptomonads and Chrysomonads has 
broken down, namely, that relating to the nature of the assimilation 
products. According to Senn, the Chrysomonads produce oil and 
leucosin, and nutrition may be holozoic or saprophytic or holophytic, 
while in the Cryptomonads starch is produced and nutrition is 
