THE ESSEX FIELD CLUB.
187
bomb crater pools and seems to approve of them. Can it be
that it has found in the water of these pools a trace of some sub-
stance from the products of the explosions producing the craters,
which encourages its development somewhat as if it were back
in the brackish water it so certainly prefers ?
REFERENCES
Fritsch, F. E. 1935. The Structure and Reproduction of the Algae.
Hustedt, F. 1928. Zur Kenntnis der Gattung Cylindrotheca Rabh.
Ber. d. Deutschen Botanischen Gesellschaft, Bd., xlvi, pp. 162-4.
------------. 1930. Bacillariophyta (Diatomeae) in Die Susswasser-Flora
Mitteleuropas, Heft 10.
Smith, W. 1853 and 1856. A synopsis of the British Diatomaceae. Two
vols.
West, G. S., and Fritsch, F. E. 1927. A Treatise on the British Fresh-
water Algae, 2nd Ed.
DESCRIPTION OF THE FIGURES.
Cylindrotheca gracilis.
1. Specimen as seen alive showing central nucleus with three chromatophores
on each side and indications of the spiral canal-raphes x 1500.
2. Portion of mounted specimen showing the two canal-raphes (dotted
bands) forming a double-threaded right-handed screw and two
fainter bands x 2200.
3. A partly disintegrated mounted specimen showing tendency to break
into spiral strips x 800.
4. Diagrammatic indication of the right-handed screwing action of the
diatom in motion.
5. A whole specimen bent into a crescent demonstrating its great flexibility.
6. Terminal part of a moving specimen bent at right angles to the main
axis when coming up against a resisting object.
7. Terminal part of a moving specimen bent into a hook owing to temporary
sticking of the little knob at the tip.
8 and 9. Two views at right angles of the expanded end of the terminal part
when forming a little knob.
THE ESSEX FIELD CLUB—REPORTS OF MEETINGS
VISIT TO NETTESWELL, LATTON AND HARLOW (825th MEETING).
SATURDAY, 16TH MAY, 1942.
After an interval of two years and notwithstanding the absence on active
service of our Excursions Secretary, the resumption, at least in part, of the outdoor
activities of the Club was attempted, and proved an outstanding success. Heavy
rain during the night had not presaged good weather, but the twenty-five members
who constituted the party were rewarded by a glorious day of warmth and sun-
shine, in delightful country, marred only by the very adhesive character of the
ground over which lay our cross-country route.
Assembled at Potter Street at 11.17 o'clock, we were met by the Rev. John L.
Fisher, M.A., R.D., rector of Netteswell and Little Parndon, who had kindly
offered to act as our guide throughout the day.
Skirting Harlow Common (now ploughed up for food production), the
visitors were pointed out a spot close to the western end of the Common, where
enemy attention in the early days of the war, producing the usual craters, had