in the measurements, even in the cells of a single specimen, they could not be relied upon as characteristics of any species. The form, how- ever, of the cells, the thickened or delicate cell-wall, the character of the contents, and the presence or absence of trigones at the angles of the cells he considered as of importance in determining the species. The paper was illustrated by drawings and specimens under the microscope. —"Notes on the Distribution of Algæ.'" By George Dickie, M.D., Pro- fessor of Botany, Aberdeen. (See p. 70.) —"On the Flora of the South of France." By James F. Robinson. Communicated by Mr. Sadler. — "Memoranda on Fir-cones chiefly in the Museum of Economic Botany, Edin. Royal Bot. Garden." By Professor A. Dickson, Glasgow. Dr. Dickson demonstrated some of the forms of spirals occuring in the cones of the Spruce Fir (Abies excelsa) by means of specimens where the cone-scales were numbered with oil-paint, different colours being used where desirable. The paint was allowed to dry, and then the cones were put up in jars with strong solution of salt. In this way he exhibited the following forms : — ^V spiral (the normal form) ; -^ spiral ; -^-^ spiral ; and conjugate double (bijagate) -JL—{=-^^) spiral.* Dr. Dickson stated that while working at these cones he took occasion (by permission of Professor Ballbur) to examine the collection of cones in the museum at the Edinburgh Botanic Garden, among which he noted the following : — A. Belonging to the ordinary series, \, \, ^, f, etc. Pinus Pinader (10 cones), P. Lambertiana (3 cones), Aiies Morinda (1 cone) P'uius Jeffrcyi (3 cones) W, Arancaria excelsa W, A. imbricata B. Belonging to series \, \, -f-, y\, y'g, etc. Abies Morinda (1 cone), Pinus Lambertiana (1 cone), and Cycus revoliUa (1 male cone) -j^, Pinus Pinaster (3 cones) -f-^, P. Jeffrey i (1 cone) -f^. C. Belonging to series i ^^ |., _3_^ _5_^ gtc. " Zauiia /nrfuracea (1 male cone) f . In another spe- cimen of the same the anthc riferous scales were in alternating whorls of 5. Pinus Pinaster (2 cones) -f-^, P. Lambertiana (I cone). Here the scales at the top and bottom of the cone exhibited a -/-j spiral. The middle of the cone, however, showed 10 secondary spirals running one way and 14 the other, being manifestly a bijugate — 5--^(=2\) spiral derived from the
series |, f, ^, -jV' ^^cf This cone is immature and somewhat irregidar in its development ; and, curiously enough, while the generating spiral above and below runs to the right-hand, the two spirals in the middle run to the left. D. Belonging to series \, J-, -5^, tt» etc. Stangeria para- doxa (male cone) i\. This is doubtless an abnormality, a cone growing upon a plant of the same species in the Edinburgh Botanical Garden ex- hibiting 13 vertical rows, of course resulting from a -^% spiral. Separate allusion mav be made to the cones of Piuus Pinaster, which seem spe- ciallv liable" to variation ; for example, in the museum there are two branches, one with 8 cones, of which there are 6 normal, with /y spiral, one with an ^V' «"<! one with a -^V arrangement ; the other with 5 cones, of which there are 2 normal, two with an Jg-, ai"l one with what seems
- Trijugate spirals have also been noted as occurring in Pine-cones (L. and A.
Bravais, "Sur la Disposition des Feuilles," Ann. des Sc. Kat. 2nd series, vol. vii. p. lOi). And Dr. Dickson has, since the Society's meeting, observed a cone of Abies excelsa, where the arrangement is a trijugate 3-7!^ ( = 6%) spiral.
t Examples of this series have been observed by Bravais (1. c. p. 93) in Pinus maritima, Dipsaeus, etc.
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