HARDWICKE'S SCIENCE-GOSSIP. 



209 



maritima), winter-green [Orienialis europaa), bog- 

 bean {Meuyanthcs trifoliata), figwort, foxglove, 

 brooklime, red deadnettle, cow-wheat, yellow-rattle, 

 wood-sage, woundwort, sea-pink {Arnicria maril'uiia), 

 sea-plantain {Plantago iiia>-iti/iia), bog-myrtle {My?-ica 

 gale), dwarf juniper (jfunipcnis naim), pondweed, 

 lesser twayblade [Listera cordata), orchis (0. Morio 

 and viaculata), water-flag, crowberry {Enipctnim 

 nigrum), squill {Scilla vcnia), cotton-grass (Erio- 

 phorum vaginattim), bog asphodel (N'arthecitmi ossi- 

 &agu/u), hart's-tongue, royal fern, etc. 



JULY NOTES, BY A FIELD NATURALIST. 



IN this month I have seen, for the first time, a 

 pair of red-backed shrikes {Laiiiiis colhtiio, L. ) 

 with the young birds. Each year I had been aware 

 that stray birds visited us in the West Midlands, but 

 could never discover eggs or nest ; this year, after 

 the breeding season was finished, the young and old 

 birds were to be seen daily fluttering about on the 

 top of the same hedge. The harsh cry is distinctive, 

 and the movement of the tail different from that of 

 any other kind of bird. I have not been able to find 

 impaled insects — the shrike's larder — in the vicinity, 

 but I have noticed the strange power of fascination 

 that shrikes possess over smaller birds, such as hedge- 

 sparrows or linnets ; although frightened, they follow 

 the dreaded charmer. With a single blow from its 

 powerful bill a shrike can cleave the skull of a small 

 bird — it is almost a bird of prey — and yet the small 

 fry hover round, as if lured to destruction. 



Towards the middle of the month I found the 

 brook swarming with tiny eels, barely an inch in 

 length, the species being the silver eel. A few 

 bigger ones must have found a way up the stream at 

 the spawning season. For ten days I kept several 

 transparent fellows with black and silver bodies in 

 an improvised aquarium. Struck with the remark- 

 able transparency of the body, I placed a living 

 specimen under the microscope. The circulation in 

 the pectoral fin was very beautiful ; the oval cor- 

 puscles appeared almost too large for the small veins, 

 but flowed ceaselessly in a never-ending stream. 

 Every detail of structure was visible, from the spinal 

 column to the heart and alimentary canal. In a few 

 weeks all these young eels, attaining to the elver 

 stage, will migrate to the weirs and rivers ; hardly 

 one will remain in the brook. 



There is even now some obscurity regarding the 

 embryology of the common eel, and the male has 

 only been distinguished from the female within the 

 last twenty-five years. Dr. Francis Day — whose 

 recent death all naturalists deplore — contributed a 

 valuable article' to "The Field,'' dealing with the 

 propagation of the species. He reviewed the ancient 

 superstitions of various authorities. Aristotle thought 

 eels were produced by spontaneous generation from 



slime. Pliny stated that a fragment of skin from the 

 parent developed into young fish. Ilelmont gives a 

 receipt for an artificial propagation as follows :— 

 " Cut up two turfs laden with May-dew, laying one 

 against the other, with the grassy sides inward ;" 

 after exposure to the sun numerous young eels ap- 

 peared. Horsehair taken from the tail of a stallion 

 was said to produce the fish, as well as parasitic 

 intestinal worms. A common tradition stated that 

 eels interbred with water snakes, and sea-coast 

 fishermen still maintain that an eel changes into a 

 conger. 



Now, however, the eggs have been proved to be 

 contained in frill-like bands of fat placed behind the 

 liver almost as far as the vent. The ova, like small 

 white dots, can be detached for the microscope. 

 Not until 1873 was it clearly demonstrated that the 

 eel was not hermaphrodite ; for no males could be 

 distinguished. In that year, Syeski, of Trieste, ob- 

 tained an eel sixteen inches in length, minus the 

 ovaries, but possessing a hitherto unrecognised gene- 

 rative organ. Since then many have been dissected, 

 and the animate spermatozoa detected under the 

 microscope in vigorous motion. The male eel is 

 smaller than the female, and rarely found in rivers. 

 The fully-developed ova do not appear to be known 

 in the rivers ; hence it is said eels breed in salt 

 water. 



The mature eggs when they are passed through 

 the abdominal cavity — there is no special duct — 

 must be deposited either in the bed of an estuary or 

 in a river.* Adults are said to descend to the sea 

 in the autumn for breeding purposes, and there is an 

 up-stream migration of elvers in the spring. But in 

 the brook that I mention, scores of minute eels 

 certainly abound in July ; they are too small to 

 ascend from the sea. I feel convinced that they are 

 hatched in the mud beneath, for it is hardly con- 

 ceivable that a delicate and fragile body, as thin as 

 a lucifer match and barely longer, could surmount 

 all the obstacles between the sea and a small inland 

 brook. I see them lie on the mud like transparent 

 threads ; and directly they are disturbed each tiny 

 creature burrows in the mud with consummate ease, 

 at home in its native element. 



The loach {Corbitis barbata) also inhabits my brook. 

 I have one before me now in a glass pickle bottle ; 

 it is about five inches long, and lies motionless at the 

 bottom of the water. The dusky colour of the back, 

 with transparent skin and numerous dark spots, 

 renders it difficult to discover lying on the mud. 

 There is one dorsal fin, two pectorals, two abdo- 

 minal and one ventral fin. The tail is undivided, 

 blunt-shaped and serrated. The course of the verte- 

 bral column is marked by a yellow line, and the 

 gills have black markings. The eyes are black with 

 a "olden rim. Teeth are visible on the roof of the 



* Is it proved that the eel is not ovo-viviparous? 



