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AND CONTENTS OF THE MOUTH. 437 



EXPLANATION OF PLATE XX. 



Figures taken from Billet : 



Fig. 17. — Articulations analogous to the pneumococci, belonging to 

 various bacteriological species on the point of passing to the 

 dissociated or to the zoogloeic state, a, A fragment of six 

 articulations of Cladothrix dichotoma in disintegration, x 320. 



b, Articulations of the same alga in more advanced disinte- 

 gration, X 1600. c, d, Bacterium osteophiUim, ready to pass 

 to the zooglo3ic state, x 600. e, A fragment of four articu- 

 lations of Bacterium osteophilum on the point of passing to 

 the scorpioidal state, x 600. Small zoogloeic group of 

 Leptothrix parasitica, Kxiizmg^ x 745. 



18. — Other analogous articulations. a. Rectilineal forms of 

 Cladothrix dichotoma in the act of passing to the zooglojic 

 state (stained first with solution of iodine, then with methyl 

 violet or fuchsine), x 600. 6, Beginning of the zoogloeic 

 state of the Bacterium osteophilum (colouring with vesuvine, 

 then with methyl-violet, and lastly with solution of iodine), 



X 600. c. Beginning of its scorpioidal state (same colour- 

 ing), X 600. f/, Same as 6, enlarged, x 1600. e, Zoogloeic 

 group of Leptothrix parasitica^ Kiitzing (colouring as in a), 



X 320. 



19. — Ramified zoogloea of Cladothrix dichotoma, formed by 21 

 branches, upon a single peduncle (same colouring as Fig. 

 2, a), X 120. 



20. — Superior endings, more enlarged, of two of the preceding 

 branches (same colouring). «, &, Tops of branches, x 600. 



c, A portion of one of them, more enlarged, containing 

 bacteria and bacilli of diflferent shape and form, x 1050. 



21. — Leptothrix parasitica, Kiitzing, vegetating on two crossed 

 stems : the one of zyynema, the other of Cladothrix (colour- 

 ing with vesuvine and methyl-violet, then with solution of 

 iodine), x 600. a, a, Stem of Zygnema. b, b, Stem of 

 Cladothrix. c, c, c. Filaments oY Leptothrix pjarasitica. 

 s, s, Their bulbs or engrafting spores. 



22. — A part of the previous figure, more enlarged (same colour- 

 ing), X 1600. c, c, c. Filaments of Leptothrix pjarasitica. 

 s, s, Their bulbs or engrafting spores. 



Original Figures : 



23.— Ears or clusters of Leptothrix racemosa, with acidulated 

 solution of iodine, a, Young cluster, with small, thin spores 

 upon their sterigms, x 1700. b, b, Groups of bacteria and 

 comma bacilli, c, A matured cluster, with sterigms and 

 thicker spores, x 1170. d, Fragment of ear, with sterigms 

 without spores, excepting two spores, still adhering, x 1170. 



24.— Cluster showing the peduncles or sterigms, funnel-shaped, 

 and the central stem, containing minute gemmules of 

 reserve, stained with weak gentian violet, x 3100. 



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