1912] GRIGGS—RHODOCHYTRIUM 163 
have been developed from an epiphytic ancestry, while endophytism 
did not appear until later. 
In contrast with this group, Rhodochytrium seems to have been 
derived from organisms which acquired the endophytic habit of 
life before any real dependence on their hosts was established. 
Moreover, the zoospores of Rhodochytrium appear to differ 
fundamentally from those of the Chytridiales. In most of the latter 
there is but one flagellum, which is often trailed along behind and 
imparts a weak jerky motion to the spore. In the genera with 
biflagellate zoospores the flagella, in most cases at least, are of the 
same type, and usually spring from different portions of the body.’ 
Sometimes also the spores put out pseudopodia and move about 
in amoeboid fashion. In Rhodochytrium the zoospores are capable 
of no such motion, but maintain the integrity of their shape with 
slight variation throughout their period of activity. The cilia, 
which are anterior, are more highly specialized structures and 
maintain a rapid vibration which propels the spore with the steady 
motion characteristic of algal zoospores in general, to which those 
of Rhodochytrium correspond in every important particular, save 
in the absence of chlorophyll. 
But the nature of the parasitism of Rhodochytriwm indicates a 
very considerable degree of departure from the algae. An obligate 
parasite which has established definite relations with specific hosts, 
even though its different races show no morphological modification, 
is certainly far from a typical alga. The loss of plastids is an 
important characteristic of the fungi, but the presence of starch 
grains looks back toward the algae. Though starch has been 
reported in several fungi, and some of them contain certain carbo- 
hydrates which give the starch reaction with iodine, such as starch 
cellulose (‘‘lichenin’’), there is no well authenticated instance of 
the occurrence of definite grains of starch in any undoubted fungus. 
Turning now to the algae along the lines suggested by LAcER- 
HEIM’S paper, we find among the protococcoid algae a number of 
5In a paper to be published almost concurrently with this (Ann. Botany, 
January 1912), the proof of which I have seen through the kindness of the author, 
Dr. J. T. BARRETT, it is shown that the zoospores of several species of Olpidiopsis 
have two flagella springing from the same point, while other species of the same genus 
are reported as uniflagellate. 
