. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . mportance by which they cai i 1 >eseparated. On the other hand, Cldorosphsera appears to be related to Chlorococcumamong the Chlorochytriese, since it produces zoogonidia (8 or more) from a single sphericalmother-cell. It is not improbable that the Algse described as species of C/dorosph&ra arethe relics of intermediate forms between Protococcus and the lowest form, viz. Chlorococcum,of the Chlorochytriese. They combine the zoogonidium-for
. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . mportance by which they cai i 1 >eseparated. On the other hand, Cldorosphsera appears to be related to Chlorococcumamong the Chlorochytriese, since it produces zoogonidia (8 or more) from a single sphericalmother-cell. It is not improbable that the Algse described as species of C/dorosph&ra arethe relics of intermediate forms between Protococcus and the lowest form, viz. Chlorococcum,of the Chlorochytriese. They combine the zoogonidium-formation of the latter group withthe formation of transverse walls in vegetative division such as occurs in Protococcuseiridis and P. dissectus. Family Autosporacese. The Autosporaccse are one of the most clearly defined families in theProtococcales. The Algce included in it are free-floating, solitary or colonial,the cells being usually associated to form very small few-celled colonies. Insome cases the colony is a coenobium with a definite construction (Coelastrese,Crucigeniea?, Scenedesmus), but in most of the other forms the colonies readily. Fig. 121. A aud B, Oocystis solitarLa Wittr. C and D, O. craxxn Wittr. E and F,O. panduriformis W. & G. S. West. G, 0. clliptica W. West. All x 485. dissociate into small groups of cells or single individuals. With few ex-ceptions the amount of mucus surrounding the colonies is small, but inKirchneriella and Elakatothrix there is a very copious mucous investmentaround each colony, and in a few other forms, such as Crudgenia and An-kistrodesmus Pfitzeri, there is a considerable mucous envelope. There isgenerally one parietal chloroplast in each cell, often very large, and notinfrequently occupying most of the cell. It may or may not possess apyrenoid. In Eremosphxra there are numerous parietal chloroplasts, andin most species of Oocystis there are several (vide fig. , C, D and E).The protoplast contains a single nucleus located
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