34 Proceedings of the Royal Society of Edinburgh. [Sess. 
after germination, the vegetative cell becomes flat, irregular in width, and 
very soon begins to twist spirally. Two individuals often twist round 
each other, and the twists may be right or left or even both in the 
same individual. 
LITERATURE. 
(1) Adler, 0., Centralb.f. Bakt., 2 Abt., 1904. 
(2) Beythien, Hempel, and Kraft, Z.f. Nahrungsmittel-Unters ., etc. t 1904. 
(3) Cohn, Beitrage z. Biol. d. P-flanze , Heft 3. 
(4) Migula, System der Bakterien , Jena, 1897. 
(5) Molisch, H., Die Pjlanze in ihren Beziehungen zum Bisen , Jena, 1892. 
(6) Warming, E., Observations sur quelques baderies qui se rencontrent sur les 
cotes du Danemark, 1875. 
(7) Winogradsky, Botanische Zeitung, 1888. 
(8) Zopf, Enticickelungsgeschichtliche Untersuchungen uber Grenothrix polyspora , 
die Ursache der Berliner W asserkalamitdt , Berlin, 1879. 
EXPLANATION OF PLATE. 
All diagrams , except jigs. 7 and 29, drawn to same scale. Magnijication 1650. 
Fig. 1. Typical example of Spirophyllum ferrugineum. 
Fig. 2. Portion of a spiral with fourteen spirals. 
Fig. 3. Appearance immediately after germination. 
Fig. 4. Individual showing very close spirals. 
Fig. 5. Two spirally twisting individuals, both showing the commencement of 
conidia formation : stained with methylene-blue. 
Fig. 6. Two individuals with long spiral lengths. 
Fig. 7. Diagrammatic representation of appearance of transverse section of 
Spirophyllum ferrugineum. 
Fig. 8. Individual showing two and a half spirals. 
Fig. 9. Example showing irregular ends. 
Figs. 9-21 show stages in the development of the organism from the conidium stage. 
Fig. 11, stained with methylene-blue and showing beginnings of conidia formation. 
In figs. 13 and 21 conidia are well developed. For further explanation see text. 
Fig. 22. Example of right-hand twisting. 
Fig. 23. Example of left-hand twisting. 
Fig. 24. Two individuals twisting round each other, both showing conidia 
formation. 
Fig. 25. A doubtful case of cell division. 
Fig. 26. Small portion of a band showing the usual prolific conidia formation. 
Fig. 27. Individual showing three and a half turns. 
Fig. 28. a, conidium; 6, first stage in the germination of the conidium. Conidium 
membrane is still attached. 
Fig. 29. Diagrammatic representation showing how the size of the organism 
is normally increased by the formation of conidia. 
(Issued separately April 24 , 1907 .) 
