98 LIVERPOOL BIOLOGICAL SOCIETY. 
dition, in which it may remain dormant for a considerable 
period before again passing into the motile state. Now 
there are two points in the life-history of Protococcus to 
which I wish to call your attention, and to which we will 
recur hereafter, viz., the motility, and the presence, when 
in a motile condition, of the pigment-spot which reminds 
one so closely of the corresponding ‘‘ eye-spot”’ in the 
Flagellate Infusoria. In order for the Protococcus to be 
able to divide and multiply in the palmella-form, it 
seems to be necessary that it should pass through the 
motile stage; and it appears also to be in this motile 
stage that the pigment is always first developed, though it 
may increase so greatly when in the palmella-condition as 
entirely to mask the chlorophyll, and give the whole 
organism a blood-red tint, in which state it is known as 
Hematococcus. ; 
Protococcus may be taken as a type of the lowest de- 
velopment of the Protococcoidex, those Schizophycez in 
which the endochrome consists ordinarily of chlorophyll- 
bodies not masked by any pigment, and which has its 
highest developments in such forms as Sczadiwm, Dictyo- 
spherium, and Characcum, with a much more differentiated 
thallus, and where the ordinary mode of propagation is 
by flagellate zoospores. 
We will now turn to another of the lowest groups of 
vegetable life, the Cyanophycee, distinguished by the in- 
variable presence of a blue-green coloring matter dissolved 
in the cell-sap, though this may again sometimes be 
masked by a brown or red pigment. In, at all events, the 
lowest of the Cyanophycee distinct chlorophyll-bodies 
have not been detected. 
One important and very interesting distinction between 
the Cyanophycee and the Protococcoidee is that, in the 
former group we have at present no well-authentivated 
