June i6, 192 i] 



NATURE 



491 



watertight, and it contains a number of ornamental 

 flower-beds surrounded by low brick and cement 

 walls, surmounted by cornices which overhang 2-3 in. 

 The surfaces of the beds are about 12 in. below the 

 top of the walls. 



On certain occasions I find worms in the back 

 street, generally of medium to a rather large size, 

 which have the appearance of being "drowned," 

 although it is very rarely that life is extinct. On the 

 esplanade they are present in large numbers. They 

 occur at all points between the beds and the sea-wall, 

 over which many of them must pass, for one can find 

 them on the watertight stone underclifT. One 

 naturally expects worms to rise after rain, but in a 

 wet season I have known eleven wet days in succes- 

 sion without a single worm appearing, while on the 

 twelfth day large numbers were to be found on the 

 pavements, the road, and the back street. On the 

 other hand, I have known them to occur after a rain- 

 storm following dry weather. In several years the 

 dates in November and January have coincided. The 

 first thing that strikes one is that the phenomenon 

 occurs only at long intervals, and then such large 

 numbers participate in it. At other times one may 

 never see a single worm. I have often wondered if it 

 were in response to a migratorv instinct. 



The mystery is how these worms mount a wall 

 12 in. high and negotiate the overhanging cornice. 

 On several occasions I have known quantities of 

 " whitebait " and other things that occur at the sur- 

 face of sea-water similarly strewn upon the esplanade 

 and roads, and I have been tempted to ask if these 

 worms have not been caught up similarly and returned 

 to earth with the rain. W. J. Lewis Abbott. 



I THINK Sir Ray Lankester (Nature, June 2, 

 p. 424) will agree wath me that earthworms when 

 underground must frequently or usually be in contact 

 with other moist surfaces. My impression is that in 

 dry weather, when the upper layers of soil contain 

 only adsorbed water and are what we call "dry," 

 earthworms seek the lower layers where the particles 

 are moist — that is, are surrounded by a surface film 

 of liquid water, however thin this may be. When 

 in such a moist layer the surface of the worm must 

 at many points be obtaining its air-supply through the 

 medium of water which is not part of itself. The 

 air, as Sir Ray Lankester says, reaches the worm 

 through the porous soil, and I think in part through 

 the moisture on the surface of the particles. The 

 statement in my letter in Nature of May 19 can ad- 

 mittedly be read as implying that the worm was partly 

 dipped in slime or mud, but this was far from my 

 meaning. J. H. Coste. 



Teddington. 



Vitality of Gorse-seed. 



By way of supplementing my letter to Nature of 

 September 26, 1918 (vol. cii., p. 65), on the above 

 subject, it may be of interest to record the fact that 

 the seedlings arising from seed which has lain dor- 

 mant in the soil for a quarter of a century have 

 produced vigorous plants. A small part of the 20-acre 

 field was not reploughed owing to its steepness, and 

 the gorse seedlings which came up on it after the 

 war-ploughing of the winter 19 17-18 have been 

 allowed to grow. They are now in their fourth 

 season of growth, and are good-sized bushes averaging 

 2 ft. in height, which have been this spring a mass 

 of bloom, like the gorse generally in this district and, 

 I believe, throughout the country. 



I can also add another year, making twenty-six in 

 all, to the vitality of buried gorse-seed ; the field in 

 NO. 2694, VOL. 107] 



question, save for the above-mentioned steep slope, 

 was reploughed in the winter 19 18-19, with the result 

 that a fresh crop of gorse seedlings appeared the 

 following summer. The field has now reverted to 

 grass, and these two-year-old seedlings are being 

 grubbed up. John Parkin. 



The Gill, Brayton, Cumberland, June 3. 



Habits of the Hedgehog. 



In the article on the hedgehog which appeared in 

 Nature of May 19, p. 375, mention is made of the 

 widespread belief that hedgehogs suck the teats of 

 cows. Although farmers have assured me that they 

 have found evidence of milk on the hedgehog, I do 

 not think that any credence can be given to the 

 statement. The belief probably arises from the ex- 

 trusion of the contents of the vesiculae seminales of 

 the buck hedgehog when crushed, kicked, or other- 

 wise injured. The vesiculae seminales are, when full, 

 extraordinarily large in proportion to the size of the 

 animal, and the milky fluid can easily be mistaken 

 for cow's milk, especially when the hedgehog has 

 rolled itself up for defensive purposes and the face 

 has become smeared with the seminal fluid. 



That hedgehogs will eat young birds I have had 

 personal experience, but I doubt if they do much 

 damage to game in this way. 



In 1906 and 1907 several albino hedgehogs were 

 found at- Goathland, Yorkshire. I attempted to cross 

 an albino doe with a normal buck, but wHen placed 

 together the latter promptly attacked and killed it. 

 In attempting to breed them in semi-captivity, i.e. in 

 a large walled garden, I found that the bucks harried 

 the does a good deal, thus rendering it difficult to 

 secure a litter, and that if the nest was disturbed the 

 mother would frequently eat her young. This proved 

 a real difficultv in the experiments. 



G. A. AUDEN. 



Birmingham, May 29. 



Principles of Picture-hanging. 



There is no need for picture-wire (Nature, May 10, 

 p. 362 ; May 26, p. 395 ; June 2, p. 438) if the principle 

 is adopted described in the Times Engineering Supple- 

 ment of April, 1919, of the application of Kelvin's 

 Five-Point principle to the picture-hanging. 



A rail, say of black enamelled electric conduit tube, 

 is supported along the wall at an appropriate height 

 on bracket-hooks fixed in the wall, and the pictures 

 are hung on the rail by two bent iron hooks fastened 

 on the back of the upper edge of the frame. This 

 gives four points of contact, and the fifth is made 

 bv a round-headed screw in the lower edge to set 

 the face at an appropriate cant. One degree of free- 

 dom is still left of a motion of the picture sideways 

 into the desired place. A picture is lifted off in a 

 trice and thrown out of the window in case of fire, 

 as of a gallery of portraits in an old mansion ; and 

 the pictures can be hung over each other, two and 

 three deep if space is limited, as in the Royal 

 Academy. 



The principle is appropriate in a modern physical 

 workshop for the support of apparatus, however 

 heavy, bracketed out from the w^all, if a plate is built 

 into a course with a projecting lip. A nail cannot 

 be driven into the glazed-brick wall, but a picture- 

 board can be kept for that purpose and placed where 

 required. The difficulty is avoided of the suspension 

 of apparatus from the roof or ceiling. 



The principle seems to have been employed in the 

 Pinacotheca of the ancient Acropolis of Athens. 



G. Greenhill. 



I Staple Inn, W.C.i, June 6. 



