102 C hod at. — On the Polymorphism of the Green 
in one plane. The cell divides in two distinct ways. In 
the first, after the first or second segmentation within the 
gelatinous cell-wall of the mother-cell, the cell-contents are 
arranged as in Tetraspora. This arrangement I have called 
tetrasporoid, or, when the dividing new cell-walls are more 
consistent, pleurococcoid. This has been very often described 
as vegetative division. 
When the cell-wall is more roundish the new cells have 
a tendency to group themselves in three directions, viz. as if 
occupying the angles of a tetrahedron : this is the tetrahedric 
division, commonly manifested in Gloeocystis 1 . This I shall 
call Gloeocystis-division. 
The cells of the Palmellaceae in every stage are, on leaving 
the envelope, capable of swarming as zoospores. As the cells 
vary greatly in size there is also great variety in the zoospores. 
In certain conditions, as for instance when the solution in 
which the Algae are cultivated becomes more concentrated, 
the cell-walls grow more consistent ; the products of division 
not being able to separate themselves from each other, 
division goes on, and then this cell is characterized as a 
sporangium. By the absorption of the separating cell-walls 
in the interior of the mother-cell, the daughter-cells can 
assume their rounded form. 
Between this formation and the Gloeocystis- stage there is 
only a difference in the consistency of the wall of the mother- 
cell, and in the degree, more or less, of absorption of the 
separating walls of the daughter-cells. Very gradual inter- 
mediate conditions are also to be found, and are the best 
demonstration that in such lower forms no true distinction 
is to be made between the so-called free cell-formation and 
the vegetative division. This is very clearly shown in the 
genera. Monostroma 2 , Palmella , and especially in Pleurococcus. 
From these three principal conditions, which are very 
equally represented in the true Palmellaceae, we can derive 
1 See Gay, loc. cit., p. 92. 
2 See Chodat, Remarques sur le Monostroma hullo sum, Bull. Soc. Bot. France, 
Session Extraordinaire, 1894, 4 1 ? P* cxxxiv. 
