2 COCCOPHYCES. 
Orver I. COCCOPHYCEZ. 
Unicellular alge. Cells either single, or many associated in 
families, tegument involute or naked, destitute of branches or 
terminal vegetation. Propagation by cell-division or zoogo- 
nidia. 
This order includes the two families Palmellacee and Protococcacea, 
with unmoveable cells, to which is attached a third, the Volvocinee, with 
mobile cells. The two former correspond to the Chreococcacee amongst 
the class Phycochromacee. Although thus removed, it would seem from 
recent researches, that there is, in some sort, a relationship between the 
Palmellacee and Protococcaceé on the one hand, and the Chroococcacee 
on the other. 
We can only direct attention here to the papers by P. Richter, in 
“Hedwigia ,’ (xix., 1880, p. 154) on Gleocystis and (xix. 1880, p. 169 
and 191), on the “genetic Connection of certain Unicellular Phycoch- 
romace@,” of which abstracts were published in the “ Royal Microsco- 
pical Journal.”* 
The conclusions arrived at are in favour of a sort of polymorphism. 
' “The lowest form of the Phycochromaces is the naked Aphanocapsa 
condition, corresponding to Palmella among the Chlorophyllophyces. 
From this naked or only slightly encysted condition is developed the 
Gleocapsa or Gleocystis form with several gelatinous envelopes; the 
Chroococeus type, when the investment is altogether wanting, or, when 
there is only a single vesicular envelope, the cawnobium types. The 
Gleocapsa type is specially adapted for exposure to the air, and growth 
upon a comparatively dry substratum; the cznobium type is developed 
in water; the Chroococceus type in water, or on a moist substratum in 
the air. With this is connected the cylindrical form, a higher stage, 
because it displays a differentiation in the direction of growth, and a 
development towards the filiform condition, This is not always de- 
veloped, and may be distinguished into stable and unstable forms; the 
latter may occur in two or three varieties, and may go through the 
following successive conditions :— 
1.—Stable Aphanocapsa and Palmelia. 
2.—Aphanocapsa and Palmella which have attained to Gleocapsa, 
Gleocystis, or cenobium type, but which always revert to the naked 
solitary spherical form. 
8.—Stable Glencapsa, Glaocystis, Chroococcus, and ceenobium forms, 
without reversion (Merismopedia ). 
4.—Cylindrical forms, the generations of which pass through the 
solitary spherical (A phanocapsa and Palmella) condition, as well as the 
Gleocapsa and similar forms. : 
5.—Cylindrical forms, which pass through only the Glaoeapsa and 
similar forms. 
6.—Cylindrical forms the generations of which revert to the Aphano. 
capsa and Palmelia condition, while the Gleocapsa or any similar form 
is suppressed, 
7.—Stable cylindrical forms (Synechococcus ). 
No reference is made in the above to the passage of Gl@ocapsa into 
the encysted filiform conditions of Sirosiphon corresponding to Palmo- 
dactyton and Hormospora among the Chlorophyllophyce.” 
* Vol. I., Second Series, 1884, pp. 98 and 201. 
