20 
Blackman and Tans ley. 
The Green Algm of which we shall treat will therefore be 
arranged in the following groups. 
Class I. Chlorophycese (Isokontae). 
Series 1. Protococcoidene. 
,, 2. Siphoncas. 
,, 3. Ulotrichales. 
,, 4. Ulvales. 
Stephanokontae. 
Series 1. CEdogoniales. 
Conjugate. 
Heterokontae. 
Series. 1. Chloromonadales. 
,, 2. Confervales. 
,. 3. Vaucheriales. 
Class V. Glaucophyceas. 
Class I. -CHLOROPHYCEAE (ISOKONTAE.) 
Plant-body unicellular , or coenocytic , or consisting of an aggregation 
of cells or coenocytes which ranges from a loosely combined indefinite 
cell-complex to a highly integrated thallus of definite form. This 
coenocytic or multicellular aggregate may retain more or less the 
isodiametric form of the typical unicellular organism or by localised 
growth may extend as a plate-like structure, or, in the majority of 
cases, as a simple or branched filament. The branches are either free, 
or joined laterally with one another, or interwoven to form a thallus of 
compact structure. 
Cell or coenocyte containing one or more briglit-green clnomatophores 
(chlorophyll unmasked by any other pigment) of very various form, 
producing starch and nearly always including one or more pyrenoids. 
Cell-wall generally giving the cellulose reactions, solid or more or 
less mucilaginous. 
Reproduction in most cases effected by naked biflagellate swarmers 
with a colourless, usually pointed, anterior end to which the two 
flagella are attached. On one side there is often an eye-spot, and the 
posterior end is rounded and possesses a more less definite basin-shaped 
chromotaphore with or without a pyrenoid. On coming to rest the 
swarmer germinates to form a new individual. In some forms these 
swarmers are facultative gametes, i.e. each is capable under certain 
conditions of fusing with a similar swarmer to form a zygote, but in 
most forms obligate gametes occur. These are similar but smaller swarmers 
( planogametcs ) which may be all alike ( isogametes ) or may be differen¬ 
tiated into megagametes, which are relatively passive ( female) and 
microgametes which are relatively active ( male ). The culmination of this 
differentiation occurs when the microgamete becomes a much-reduced swarmer 
Class II. 
Class III. 
Class IV. 
