HARDWICKE'S SCIENCE- GO SSIP. 



137 



Aquarium and elsewhere. In the lecture theatre 

 were exhibited Dr. Hudson's drawings of micro- 

 scopic objects shown in a new manner as transpa- 

 rencies ; Mr. Spottiswoode's splendid polarizing 

 apparatus, and various objects shown with the 

 oxyhydrogen microscope by How & Co. One of 

 the most satisfactory results of the soiree is the 

 great impression produced by it on the foreign 

 scientific men, who appear to have been greatly 

 surprised at the extent and nature of the gathering. 



Markings ox Suiurella Gemmae. — Would 

 any correspondent, of yours inform me how to treat 

 a slide of Surirella Gemma (dry-mounted for a ■ S 1 T ), 

 so as to bring out the markings given in Dr. Car- 

 penter's book on the Microscope, fifth ed. p. 214? 

 I have failed with Beck's T ' 5 imm., but suspect 

 that the failure arises rather from a defective mode 

 of illumination than from want of magnifying power. 

 — Isabella L. Bird. 



Varnish for Glycerine Mounts.— I should 

 feel greatly obliged if some microscopical reader of 

 SciENCE-GossiPcould tell me of some trusty varnish 

 for finishing off slides mounted in glycerine. I know 

 of several, but they would have to be made at home, 

 and 1 want to buy ready-made at a shop, so that it 

 could be applied at once. Many valuable slides in 

 my cabinet have been destroyed through the varnish 

 I have used in finishing having " run in." — Charles 

 William*, RecHand. 



ZOOLOGY. 



Hatching Silkworms' Eggs. — The silkworm 

 {Bombyx mori) is a native of China. Like other 

 Lepidoptera, the silkworm lays eggs (which are 

 nearly round, and rather less than a mustard- 

 seed), and exists in the three usual states. In 

 April the eggs should be exposed to the heat of the 

 sun, and they will begin to hatch ; they should be 

 placed in cardboard boxes, covered over at the top 

 with a net. At birth, the larva is about one-third 

 of an inch in length. Its colour for the first ten 

 days is generally a bluish- black, afterwards a bluish- 

 white, and when ready to spin, a semi-transparent 

 yellow colour, like a ripe white grape. The time 

 occupied during the larva state is about thirty days, 

 or may be extended to forty-five by varying the 

 temperature of the cocoonery. As soon as hatched, 

 they should be fed on lettuce-leaves until they begin 

 to get large, when they must be fed entirely on 

 mulberry-leaves. When ready to spin, they raise 

 their heads, and a portion of their bodies, moving 

 them about as if in search of something, until they 

 find a suitable place for the construction of the 

 cocoon. This they perform by attaching the slender 

 silk filament at various points ; and, then by a 

 rotary motion of the head, spinning the silky thread 



around them, until completely hidden from view. 

 Count Dandolo estimated the length of this thrtad 

 at about six hundred and twenty yards. In two or 

 three days, the cocoon will be completed, and the 

 insect will have undergone its first metamorphosis, 

 and entered the chrysalis state ; in eight days the 

 cocoons may be gathered. The chrysalis, when not 

 destroyed, requires a period of from fifteen to 

 twenty days before undergoing the second meta- 

 morphosis, when the moth makes its appearance, 

 forcing its way through the cocoon, breaking the 

 slender threads of silk ; thus diminishing, if not 

 destroying its value. The males first appear, and 

 are readily recognized, as they are smaller than the 

 females, move about more briskly, keeping their 

 wings in a continual flutter without flying. The 

 moths eat nothing, and live but a few days, during 

 which time the female deposits her eggs, to the 

 number of about five hundred, which should be put 

 into a dry drawer, until the following spring, when 

 they will require the same attention as before. — 

 Joseph G. Henderson. 



The Silvery Hair-tail {Trichiurus lepturus) 

 found in the Moray Eirth at Banff. — On 

 April 3rd a mutilated specimen of the above rare 

 fish was found by some boys in the sea amongst the 

 rocks near our harbour. When taken out of the 

 water, the tail and a portion of that part of the body 

 was found to be wanting, and the dorsal fin, except 

 a few of the rays, was completely gone, as also the 

 pectorals. The head likewise was considerably 

 damaged. In length, although thus broken, it 

 measured IO5 feet ; in breadth, about the middle, 

 about 1 foot; and in thickness from 2 to 2j inches. 

 When entire, this example must have been over 12 

 feet in length. Its appearance, notwithstanding 

 that it had been dead and tossed about some time, 

 was like that of a long sheet of highly-burnished 

 silver. — Thomas Edwards, Banff. 



Capture of Cynthia Huntera in England. 

 — Mr. Lovek in's inquiry in your Eebruary number 

 in reference to the reported capture of this species 

 in England, induces me to inquire whether there is 

 any record of its capture there at anytime previous? 

 The close resemblance of Huntera to Cardui may 

 easily mislead any one not acquainted with both so- 

 called species. My opinion is that they are mere 

 varieties, Huntera being the more common of the 

 two in this vicinity. Large eye-spots near the 

 margin of the underside of the secondaries is the 

 distinctive mark of Huntera, those in Cardui being 

 small : but a large series of Huntera would show 

 spcts of many different sizes. Some year or two 

 since I obtained from Ohio a very remarkable 

 variety of Huntera, differing from the type, inas- 

 much as that the primaries were of a very dark 

 brown, nearly black, with the exception of a rather 

 large discal patch of the ordinary orange-colour, a 



