8 THALLOGENS. 



P. vlridis, green ; in gutters, etc. 2. Palmella cruenta, deep red ; on 

 stone walls. 3. Chrooc6ccus lufSscens, russet; wet rocks, in springs; 

 Pig. U, A, B, C. 



Tribe 2. Volvocaceae.^Int. cell-division ; active zoospores associ- 

 iited in a gelatinous matrix of various forms, in fresh water. Few 

 genera. 1. Volvox globdtor, green ; in ponds. Fig. 12. 



Tribe 3. Bacteriacese. MIcbobes. — Transverse Fission. Cells 

 cylindric, rigid, very active ; isolated or joined end to end, forming 

 filaments ; without chlorophyl ; usually microscopic. Omnipresent. 

 Several genera. 



1. Micrococcus (perhaps near Sacohardmyces, in Fungi) ; cells 

 rounded. Several species ; in smallpox, scarlet fever, measles, diph- 

 theria, gout, blood-poisoning from Poison-Oak (Rhus toxicodendron). 

 tA. prodigibsus, Blood-uain ; red, on spoilt meat, vegetables. M. 

 PflUgeri, on fishes ; phosphorescent, making luminous patches in the 

 sea. 2. Bacterium, cells rod-like, rigid. Several species ; in putrefac- 

 tion, filth. 3. Bacillus, like 2, hut more slender. Several species; 

 in leprosy, hydrophobia, typhoid fever, malaria, consumption, catarrh, 

 hog-cholera, hen-cholera. 4. C6mma Bacillus, cells curved like a 

 comma ; in Asiatic cholera. 5. Leptothrix, very slender. Several 

 species ; in decayed teeth, skin-diseases. 



Tribe 4. Nostocacese. — Transverse Fission. Cells rounded, joined 

 end to end, with one larger cell (heierocyst) at intervals, the whole 

 forming a moniliform filament immersed in a gelatinous matrix. 

 Fresh water, damp earth, stones, etc. Many genera; some are the 

 gonidia of lichens. 1. Nostoc edw/e, fresh water ; China. N. cacicula, 

 Catoosa Springs, Ga. N. commime, Falling-Staks, Star-Jelly; 

 appearing suddenly on lawns, etc., after rain. Common. One species 

 fossil, in Tertiary. 



Tribe 5. Oscillatoriaceae. — Fission. Cells with chlorophyl ; in 

 filaments with oscillating movement* ; here and there a heterocyst. 

 Several genera. 1. Oscillatoria, several species, dark green ; in 

 water, wet earth. 2. Trichodesmium Ehrenbergii, brick-red filaments 

 on the great oceans, and on the Red Sea, which gets its name from 

 them. 3. Rivul^ria, lika 1, but with radiating filaments. Several 

 species ; wet places. 4. Scytongma, filaments branching. Several 

 species ; habitat of 3. 



Div. 2. — Alg^ ViRa;, True (higher) Seaweeds. Lessons V., 

 VI. Fossil in Silurian, thence upward. 6 Tribes : 



Tribe 1. Conjugatse. — Fission; conjugation. 3 Sub-Tribes: 



Sub-Tribe 1. Diatomacese (Bacillaridcece). — Described, Lesson V. 

 Many genera ; common in fresh or salt water, damp earth. 1. Navicula 

 mridis, frustules solitary, longer than broad ; valves with a distinct mid- 

 dle line ; Fig. 13, A. 2. Grammat6phora mnrina, frustules longer than 

 broad, without middle line ; plate-like, adherent ; Fig. 14, A. 3. Di- 

 itoma, frustules longer than broad, coherent. D. flocculbsum, ditches, 

 \~\'2" long. 4. Bacillaria paradoxa, only species ; frustules stick- 

 like, coherent by their sides, but slipping constantly back and forth. 

 West Point ; Gt Brit. 5. Melosira sulcata, frustules cylindrical ; 

 valves adherent into a stout filament ; Fig. 14, B. 6. Actinoptychus 

 sendrius, valves shield-like, divided into light and dark compartments ; 

 Fig. 14, C ; B and C fossils, in Tertiary, Richmond, Va., making, with 

 many other species, a deposit 30 feet thick and several miles in extent. 



