ON THE DISTRIBUTION OF TROUT IN SUFFOLK.
99
In due course the eggs hatch, when the baby Trout in their first stage are known as alevins. For long they are under an inch in length and very helpless ; the mouth organs do not develop, but under the body of each little fish is a considerable yolk-sac, the contents of which are gradually assimilated as nourishment. As soon as this sac is quite absorbed,the mouth develops into being ; and the fish, now perfected miniatures of the adult, are collectively called fry. The rate of its increase in size is in direct ratio to the food-supply and suitability of the surrounding water. Like the stag, it attains its prime in about six years, and remains in that condition for a few more, after which period it declines, ceases to breed, and grows lean and lanky with a great hooked lower jaw.
Their food consists of almost every kind of small aquatic life, such as freshwater Shrimps (Asellus aquaticus, Linn.), worms, snails, spiders, small fish, beetles and the subaqueous stages of various other insects, with any flies and caterpillars that they are able to annex from the surface of the water. Old Trout will take also shrews, frogs, smaller editions of their own kind, and in fact, anything they are capable of Coming at and swallowing. In the everlasting struggle for existence, very numerous enemies attack this fish : their ova are consumed by wading birds and cannibalistic fish, including eels ; alevins have to run the gauntlet of other predatory fish, kingfishers, herons and, in places, such birds as grebes and cormorants ; finally the fry fall to Otters, and adults to man himself. They will thrive in almost any quite-pure waters, throughout the temperate zone ; but, whenever they occur in lakes or sluggish streams, fast running affluents are necessary for their spawning and, of course, slack competition helps their growth.
LUMINOUS BY
CLAUDE
MORLEY,
CENTIPEDS. F.E.S.,
F.G.S.,
F.Z.S.
THE investigations of William Kirby of Barham, F.R.S., into the economy of these repulsive but most interesting Myriapoda, have been hitherto overlooked by modern scientists ; in his day, they feil within the scope of Insects and the typical species bcolopendra electrica, Linn., relegated to the genus Geophilus - b a m ° u e l l e in 1819, p. 117) was doubtless confused with allied ones. Kirby found both carrots, " which form a valuable part of the crop of sand-lands in Suffolk," and parsnips to be much mjured by the small Centiped, Geophilus electricus, and another myriapod Polydesmus complanatus, Linn., that eat into the upper r00ts rimV ( K i r b y a n d S P e n c e > Introd. Entom., Ed. 1859, ln T ^ e former is also carnivorous, for it assimilates the ommon Earthworm (.Lumbricus terrestris, Linn.) and " the Rev.
100
LUMINOUS
CENTIPEDS.
Revett Sheppard of Offton in Suffolk, saw one attack a Worm ten times its own size, which it twisted around like a serpent, finally mastered and devoured " (loc. cit. p. 148). T h i s Electric Centiped is phosphoric, and its light may defend it f r o m foes : M r . Sheppard watched a Carabus-beetle running round a shining one, as if wishing to attack it but afraid to do so on account of its light (1. c. 409). At another time* he took one of these Groundbeetles Carabus violaceus of Linn., and touched his skin with its saliva, which " caused as m u c h pain as if he had r u b b e d his face with spirits of wine after shaving " ; b u t such was not always the case, and he considered its caustic nature due to t h e beetle's food, which there was reason to think at that time had been Geophilus electricus (1. c. 420). I have enjoyed the sams experience in Suffolk f r o m C. violaceus, whose fluid seared like caustic acid ( E M M . 1911, p. 214) and is, actually, so powerful an irritant poison as to slay a Frog, bitten by this beetle in the leg (Canon Fowler, 1. c. 1882, p. 188). T h e light of G. electricus, a common British species that is often visible at night in gardens and lives u n d e r clods of earth during the day, is confined to no particular part b u t " proceeds f r o m the whole body " (K. and S. 509) ; though what " peculiar Organisation contributes to the production of light u n d e r the whole integument of G. electricus " could not be ascertained : both Macartney (Philos. T r a n s , 1810, p. 281) and Kirby f o u n d " e f f u s i o n of a luminous fluid on its surface and that this may be received upon the hand, exhibiting phosphoric light for a few seconds afterwards," and that it will not shine in the daytime (K. and S. 512). Quite likely Suffolk peasants loosely call these animals Glow worms, as Geophilus carpophaga of Leach is termed at Heacham in Norfolk, where that species is of frequent occurrence at Roydon, j u s t over the Suffolk border. But the sole comital specimens I have seen were taken hibernating near Browston Hall in Lothingland during January 1933 by M r . Ellis (teste Birks), and in the brick-floored scullery of M o n k s ' Soham H o u s e during the first twenty years of our residence : since 1924 it seems to have been expelled by paraffin oil. Kirby makes a final reference to " the light-giving Centipede best known as the Electric, which *Both this and the last Observation go to show intimate association, if not superficial relativity, between myriapodous LITHOBIIDAE and coleopterous CARABIDAE, which is further exemplified by a dry Carabid larva, in my collection from the London district, with its jaws still firmly fixed in the body of an Earthworm (Lumbricidae, sp. ?). T h a t relativity is not more than superficial is rendered doubtful by the actual breeding of one of our most abundant parasites of the hymenopterous genus Proctotrypes, calcar of Haliday, from the Common Centiped Lithobius forficatus, L. (Entom. iii, 1867, p. 342), other kinds of which genus are normally parasitic upon larvae of Carabidae, e.g. Nebria brevicollis, Fab., Pterostichus vulgaris, L. (Curtis, Farm. Ins. 131, 198) and P. madidus, Fab., whence five Proctotrypes ater, Nees, were sent me from Barnsley in Yorks by M r . Clutten in August 1924.—C.M.
LUMINOUS
CENTIPEDS.
101
is remarkable for emitting a vivid phosphoric light in the dark ; this is produced by a viscid secretion that, when adhering to the fingers as I have observed, gives light independently of the animal. This species frequents beds ; its object in doing so may be to search for Bugs [Cimex lectularius, L.] and other insects that annoy us during repose " (Bridgewater Treatise on the Power of God 1835, ii, 69 ; Ed. Bohn 1853, ii, 52). It has not appeared upstairs in my house ! Little attention has been paid such luminous Myiapods since 1840, when Knights gave us his exaggerated picture of G. electricus in Animated Nature, ii, figure 3756, until Dr. Brade-Birks discovered the luminosity's composition in 1919 (Ann. and Mag. Xat. Hist. v., 1920, pp. 1-30). T h e n both sexes at all ages of at least seven species, including the above two, were found to emit such luciferin upon Stimulation by an electric current applied directly to the animals' bodies by electrodes laid by contact-wires from an induction-coil in the dark, whereon direct photographs were obtained by placing the body on a film with the sensitised surface downwards. T h e fluid given off from both sides of the venter is viscous, colourless, smelly and acid in reaction, containing all essentials for producing light and forming crystals. Its purpose is certainly protective, since the natural exsertion is far less when the animal is simply handled than when it is attacked by Ants : Carabids were not, unfortunately, introduced.
A NATURALIST'S
BIOGRAPHY:
MR. JOHN DAVEY HOY, BY WALTER A .
1797-1839.
BROOK.
IHERE is one person, that I do not find named in the Retrospect of buffolk Naturalists (p. 62 supra), of whom we should like to know more : Hoy of Stoke-Nayland, who was so interested in bird"te, Dr. Laver writes to the Hon. See. early this year. It was a happy thought, though unfortunately little light is recoverable upon the scientific attainments of our subject. T h e family name hrst emerges in Suffolk annals scattered through a half-dozen Y'lages among those of the 1524 Subsidy ; and appears to be uerived from the Welsh adjective, hoyw—alert, sprightly, lively, gay—or possibly fr 3m Flemish, hui—a hoy—in this case suggesting some sea-faring origin a couple of centuries earlier, though certainly not in this County.
Restricting our enquiry to the Stoke-by-Nayland family, the eariiest reference is to that John, born in the parish during 1739, 17ATA d l e d i n 1 7 9 9 (Torlesse, S - b y - N . , p. 85), who married in V M A n " Strutt of Boxford (Mar. Lic. Archd. Sudbury, p. 289 /2) ; ne was bürn in 1734 and died " at her son's house, Walthamstow,"