HARDWICKE'S SCIENCE-GOSSIP. 



7i 



tropical climates, where many kinds of trees have two 

 or three successions of leaves in a year, a correspond- 

 ing number of layers will be formed. The method 

 of ascertaining the age of an exogenous tree by 

 counting the number of concentric rings visible would 

 be absolutely correct, if one could be quite sure that 

 observers provided against all possible causes of error. 

 But it has been shown by Dr. Lindley that, in con- 

 sequence of the extreme inequality in thickness of 

 the annular layers of wood on the opposite sides of a 

 stem, a person who judged of the whole age of a 

 tree by the examination of the layers of the stunted 

 side only would commit errors to the amount of 60 

 per cent, or more. — F. C. D. B. 



Castor. — I think Mr. Ingersoll has made a slip of 

 the pen (or else there has been a printer's error in the 

 brackets), in calling the secretion of the male of the 

 musk deer, "castor ; " and there has been a further 

 oversight in assigning to that animal a habitat in 

 Africa. Castor is the secretion of the ano-preputial 

 glands of the beaver {Castor fiber) of Europe, Asia, 

 and America, the American being the least esteemed. 

 If your contributor is referring to musk, that is the 

 secretion of the preputial glands of the musk deer 

 (Mosc/n/s moschifenis) of Central Asia. There is 

 a musky secretion from the inguinal follicles of certain 

 African antelopes, but this is not used as a drug. 

 Antelopes of South Africa, Abyssinia, Nubia, Tripoli, 

 Morocco and Senegal are known to emit this musky 

 or sub-musky odour. — Viator. 



Croaking of Frogs. — Having kept tree-frogs 

 myself, I was much interested in the note by M. R. 

 in the February issue of Science-Gossip. My frogs 

 were kept in an old aquarium specially fitted up for 

 their requirements ; on no occasion, however, did I 

 hear my pets croak, and they never entered water 

 voluntarily. As they came from Germany, however, 

 no doubt they partook somewhat of the phlegmatic 

 seriousness of the proverbial German. I should 

 much like to possess specimens of the species M. R. 

 refers to, and would be exceedingly obliged if that 

 gentleman would kindly inform me where, and from 

 whom, they may be obtained. I always have under- 

 stood that tree-frogs passed the winter in a torpid 

 state, buried in the mud at the bottom of stagnant 

 pools ; and also, that they deposited their eggs 

 therein previously to leaving the water. My frogs 

 were quite as voracious as those possessed by M. R., 

 and would take prodigious leaps after their prey and 

 alight upon it with unerring accuracy. My pets, 

 however, never attained to a greater size than an 

 inch in length, two of them were green and two 

 brown, and they never changed their colour, only 

 appearing a little brighter after a cast of skin. I had 

 an old frog once who used to croak dreadfully, he 

 lived in a conservatory adjoining the house, and his 

 croaking could be heard quite plainly in the house. 

 He never croaked, however, unless he could find a 

 pan of water to sit in, but so surely as water was left 

 about on the floor he would get into it, and laying his 

 throat quite flat on the surface of the water would 

 give forth such a series of croakings and gurglings as 

 made one's blood run cold. — W. Finch, jun., 158 

 Arkivright Street, Nottingham. 



Ornithological Voracity. — It is not at all un- 

 usual for birds to be suffocated whilst endeavouring 

 to gorge food too large for them (Science- 

 Gossip, p. 43). Quite recently I saw an account 

 in a sporting paper of a heron which had choked 

 itself in an endeavour to swallow a trout over 2 lbs. 

 in weight. Mention was also made a short time 

 since in the " Field " newspaper of a young pheasant 



being choked by swallowing a mouse. I once 

 dissected a young heron, in whose stomach I found 

 a very large water-rat, which occupied the whole of 

 the bird's stomach, so that its long tail remained in 

 the throat of the bird. How so young a bird had 

 managed to swallow such an enormous bolus was 

 truly a mystery.— IF. Finch, jun., Nottingham. 



NOTICES TQ~CQRRESPONDENTS. 



To Correspondents and Exchangers.— As we now 

 publish Science-Gossip earlier than formerly, we cannot un- 

 dertake to insert in the following number any communications 

 which reach us later than the 8th of the previous month. 



To Anonymous Querists.— We must adhere to our rule of 

 not noticing queries which do not bear the writers' names. 



To Dealers and Others.— We are always glad to treat 

 dealers in natural history objects on the same fair and general 

 ground as amateurs, in so far as the "exchanges" offered are fair 

 exchanges. But it is evident that, when their offers are simply 

 disguised advertisements, for the purpose of evading the cost of 

 advertising, an advantage is taken of out gratuitous insertion of 

 " exchanges " which cannot be tolerated. 



We request that all exchanges may be signed with name (or 

 initials) and full address at the end. 



J. J. Wolfe.— Get Dr. Cooke's "Ponds and Ditches," 

 published by S. P. C. K., price vs. 6d. ; also "A Thousand 

 Objects for the Microscope" (with illustrations), by same 

 author, price is. (Warne) ; also Rev. J. G. Wood's little book 

 on " Microscopic Objects." Newman's " British Butterflies and 

 Moths" contains capital figures of every species. You can 

 now get a decent student's microscope for about ,£3 10s. 



Amator Natur/E. — A correspondent remarks that the 

 insects described with this subscription are the females of the 

 black ant. 



R. C. C. — Dissolve a little of the best loaf sugar to saturation 

 in a little hot distilled water. Place a little on a glass slide 

 and gently heat the latter until the water is evaporated. The 

 sugar-crystals will remain behind on the slide. Flowers are 

 fertilised by minute insects getting inside when the myriads of 

 minute male and female flowers are collected together. 



A. Ross.— The "Dutch Rush" to which Mr. M. Williams 

 alluded is a species of Equisetum, perhaps E. hyeniale, which 

 goes by the name of the "Scouring Rush." 



J. Taylor. — We are sorry that the limits of space make it 

 impossible to admit your lists. 



E. R. Fairleigh. — Coloured plates are not now issued with 

 the monthly parts of our Magazine. They ceased to be issued 

 at the end of 1885. 



EXCHANGES. 



Wanted, pitchstone from Arran. Will give in exchange 

 rocks or fossils or coal-plant sections.— James Spencer, 8 Salis- 

 bury Place, Halifax. 



Wanted, fossil wood from all formations. Will give in 

 exchange good transparent sections of coal-plants and spores. — 

 James Spencer, 8 Salisbury Place, Halifax. 



For exchange : — " Popular British Entomology," " Student's 

 List of British Coleoptera," by Pascoe, new 1882; also " Dog 

 Fiend" and " Privateersman " (Marryat) ; "Saucy Arethusa" 

 (Chamier) ; "Sylvester Sound;" "The Count of Monte 

 Cristo" (Alexandre Dumas) ; "Windsor Castle" (Ainsworth) ; 

 "Young England" for 1886 (unbound), in good condition. 

 Wanted, natural history objects of all kinds. Send lists. — 

 E. O. Meyers, Richmond House, Hounslow, W. 



" Practical Histology," by Dr. Thiu (see " Hogg on the 

 Micro, "p. 224, nth ed.), in exchange for slides of an interesting 

 description. — Chas. Woods, 55I King Street, Jersey. 



Anatomical slides (36), in exchange for others less scien- 

 tific. — W. Woods, Red House, Wheatley, Oxon. 



What offers for Muspratt's " Chemistry as Applied and Re- 

 lating to the Arts and Manufactures," parts 7-1 1, 14-21, 23-44, 

 thirty-five parts in all ?— A. E. Fasnacht, Clayton, Manchester. 



For exchange, a perfectly new and unsoiled copy of J. G. 

 Romaue's work on "Jelly-fish, Star-fish, and Sea-urchins," 

 for a copy of White's " Natural History of Selborne," or a few 

 good fossils or foreign shells.— E. White, 3 Pixholm Grove, 

 Dorking. 



Wanted, Tyndall's Belfast Address to the British Associa- 

 tion : also Darwin's " Variations of Animals and Plants," 

 "Origin of Species." Cash or exchange (state desiderata). — 

 Mark L. Sykes, New Lane, Winton, near Manchester. 



Wanted, Dana's "Mineralogy" (edition 1887), also a book 

 on the geology and mineralogy of the United States. — Thomas 

 W. Reader, 171 Hemingford Road, London, N. 



Science-Gossip, back numbers for 14 years, in exchange for 

 books on Botany. — John Bracewell, 178 Jubilee Terrace, 

 Accrington. 



