HARDWICKE'S S CIENCE -GOSSIP. 



well as the feet of the Black-cock, a not uncommon 

 bird on our moors, tells me that the latter bird can 

 always be identified by its peculiar footmarks. 



The same friend drew my attention to the curious 

 continued note made by the bird, first in a higher 

 pitch, and then in a lower. This note has sucli an 

 effect that Gilbert White says it produced a vibra- 

 tion through the structure of a summer-house, per- 

 ceptible to the persons who were sitting within. 

 I cannot decide how this peculiar sound is produced, 

 but I suppose it is by means of the inferior larynx, 

 which, however, is not so much developed as in a 



singing bird (fig. 5) ; 

 the trachea, however, 

 has two pairs of very 

 strong muscles, one 

 pair arising from the 

 sternal ribs, and in- 

 serted into it below its 

 middle, the other run- 

 ning along it behind, 

 and beginning at the 

 top of the inferior 

 larynx. These may 

 both act on the length 

 of the trachea, and 

 also make tense or 

 re laxlhe bronchi and 

 their tympaniform 

 membrane; and thus 

 account for the change 

 of pitch of the note 

 above alluded to. The 

 bird can also emit a 

 faint cry or chirp, and 

 also produce a sharp 

 snapping sound, either 

 by the striking to- 

 gether of the wings, or 

 the closing of the 

 mouth. The upper 

 larynx and mouth are 

 muscular, the latter 

 having many callous 

 points directed back- 

 wards. The cornua of the hyoid are like those of the 

 "Woodpecker in position. The sternum has an enor- 

 mous keel, the bird, like the Swift, being wonderfully 

 active on wing. The bones are very light and cellular, 

 so that the rather large skull only weighs four grains. 

 The ear is much developed, as in the Owls; the semi- 

 lunar or rather circular canals occupy nearly all the 

 posterior walls of the skull, and are surrounded by 

 very cellular bone. The eye is flattened behind, 

 like the Owl, and projected in front, the lens globular 

 in front and flattened behind, and here brought near 

 o the retina, which is very deficient in the absorb- 

 ing pigment ; the iris is very expansible: provision 

 seems made for vision in obscure light, lor a 



Fig. 5. Larynx of Fern-owl. 



pretty extended field of view, and for the distinct 

 sight of near objects. But on these points, as in- 

 deed on the use or uses of the pectinated claw, it 

 behoves the writer to speak with some diffidence. 



It is probable that both the Cuckoo and the Night- 

 jar occasionally remove their eggs from one place 

 to another. For the Cuckoo's doing so, at least in 

 the case of the beautiful cuckoo of South Africa, 

 we have Le Vaillant's authority, and that of other 

 people in England ; we have heard the same of the 

 Night-jar, but only from one countryman. 



A friend tells us, with respect to swallows, that 

 during the great drought this last summer, the 

 swallows, which usually build in an outhouse of his, 

 not being able to find mud, laid their eggs and reared 

 their young on a cross-beam of the room, without 

 any nest of plastic material at all. R. G. 



T 



DECOLOURING AND STAINING 



VEGETABLE TISSUE EOR MICROSCOPIC 



EXAMINATION. 



By Geohge D. Beatty, M.D. 



HE following is a brief statement of the pro- 

 cesses I use to discolour and to stain vegetable 

 tissues : — 



To effect the discolouring, I use several agents : 

 alcohol, Labarraque's solution of chloride of soda, 

 nitric acid and water, equal parts, adding to each 

 ounce, one drachm of chlorate of potash. 



Alcohol will discolour some petals and leaves, and 

 render them beautifully transparent ; but when they 

 are stained, the epidermis aud stomata are imper- 

 fectly visible. 



The nitric acid mixture brings out with great dis- 

 tinctness the forms peculiar to the parenchyma ; but 

 it has a tendency to injure the epidermis. 



The chloride of soda is, by far, the best 

 decolorizer. It bleaches leaves and petals, and 

 renders them transparent in from six to forty-eight 

 hours. 



After removing the tissue from this fluid the 

 chlorine must be entirely eliminated. To effect this 

 it must be placed for eighteen, sometimes twenty- 

 four hours, in temperate water. The water should 

 be frequently agitated, and changed several times. It 

 should be in a quart vessel. 



If aniline blue be the dye, the next step is to 

 place the tissue in 90 to 95 per cent, alcohol, acidu- 

 lated with eight drops of nitric acid to the ounce. 

 In this it should remain oue hour before being 

 placed in the dye. 



I prepare my blue dye by carefully mixing in a 



mortar an ounce of 95 per cent, alcohol, with one 



half or one grain of aniline. It is afterwards fil* 



1 tered, and alcohol added to make up one ounce ; 



finally is added one drop of nitric acid. The half- 



