1883.] 



MICROSCOPICAL JOURNAL. 



177 



ing to one valve and the other to the op- 

 posite valve. In 24 to 36 hours the striated 

 portions broke up into fragments resem- 

 bling the iron cramps ot carjienters. " In 

 fact, the striation is due to the juxtaposi- 

 tion of a number of these little cramps 

 along the length of the frustule, probably 

 cemented together originally." 



— The latest type slide of Tvlr. J. D. 

 Moller contains 1,600 arranged diatoms 

 and is offered for sale at 1,600 marks — 

 about $370.00 at the lowest calculation. 

 A plate with 800 and another with 400 

 diatoms are also made. All type slides 

 are put up with monobromide of naphtha- 

 line, and test-objects from Mr. Moller 

 may now be obtained mounted in balsam 

 monobromide of naphthaline, or solution 

 of phosphorus. 



— Almost every year the young trout 

 bred in the piscicultural basins of the 

 College dc France become attacked about 

 July, by a malady that carries off great 

 numbers of them. This is caused b}' a 

 cihaled infusorian known as Iclithyopli- 

 thirius ?nnltijilii\ which lives upon the 

 epidermis and causes inflammation of 

 the skin. There has lately been ob- 

 served, by Mr. L. F. Henneguy, an- 

 other parasitic infusorian which attacks 

 the young fish almost as soon as they are 

 hatched, and destroy great numbers of 

 them. This parasite covers the epidermis 

 in such numbers that the epidermal cells 

 are quite concealed from view. Each 

 infusorian has three flagella. The ani- 

 mals resemble Stein's Bodo caiidattis in 

 shape, and have been provisionally named 

 Bodo necator. They measure 0.02 mm. 

 in length by 0.0 1 mm. wide, and are the 

 first ectoparasitic flagellata that have been 

 described. — Coniptes Rendus. 



— A dead black color for brass is fre- 

 quently desired by amateurs in making 

 accessory apparatus, and we had had in- 

 quiries, from time to time, as to how it 

 can be obtained. For the inside of tubes 

 a good black is obtained by mixing fine 

 lamp-black with ordinary lacquer, and ap- 

 plying it with heat. Only one or two 

 thin coats should be applied, or the sur- 

 face will become glossy. The lacquer 

 used is merely a solution of shellac in 

 alcohol. Many brass parts are blackened 

 or bronzed by the application of a dilute 

 solution of platinium chloride, which im- 

 mediately gives a dark color to the metal. 

 Corrosive sublimate dissolved in vinegar 

 ( about 30 grains to the ounce ) will also 

 give a bronze color. To get a good 



black, a solution of copper wire in nitric 

 acid will serve best of all, but tlie articles 

 must be so highly heated that soldered 

 joints will be loosened. 



— It has been found, by M. E. Panchon, 

 that the sound vibrations of the highest 

 note audible to the human ear are 72,000 

 per minute. Mr. Galton has made a 

 hydrogen whistle which is said to produce 

 312,000 sound vibrations per second. 

 This whistle is 14 inches long by 0.04 inch 

 in diameter. Such exceedingly rapid 

 vibrations are quite inaudible to us, but 

 the instrument has been devised to 

 test the hearing power of insects, which 

 is very acute. The results have not yet 

 been published. 



— Mr. A. D. Michael states that for 

 mounting insects in balsam the creatures 

 may be killed in hot water or spirit. He 

 prefers to use hot water for hard insects 

 and acari because it causes them to ex- 

 pand their legs. Minute flies are best 

 killed in alcohol. In mounting he advises 

 not to use quite enough balsam to fill the 

 space under the cover, as the balsam sup- 

 ports the cover if it does not reach the 

 edge, while if it extends to the edge it 

 is apt to draw down the cover and crush 

 delicate objects. He recommends thin 

 glass beads to support the cover-glass. 

 To mount hydrozoa, polyzoa, etc. with ex- 

 tended tentacles, he prefers to use alcohol 

 for killing them in this way : The objects 

 are placed in a watch-glass and left undis- 

 turbed until their tentacles are well-ex- 

 tended. A small drop of spirit is then 

 run down the side of the glass but not 

 on the polypes. The tentacles will then 

 probably be withdrawn, but after a time 

 they will be again extended. Add then 

 another drop of spirit. After two or three 

 repetitions of this operation the animal 

 seems to get drunk, and then alcohol may 

 be added freely. 



— Dr. William B. Carpenter has pre- 

 sented to the United States National 

 Museum a fine series of slides illustrating 

 his monograph on the genus of foramini- 

 fera Orbitolites, which will be published 

 as one of the reports of the " Challenger" 

 expedition. Dr. Carpenter makes four 

 species. O. termissitna, a very delicate 

 shell, specimens of which are difificult to 

 obtain, O. tnargiitalis, O. duplex^ and 

 O. complanata. There are 47 slides in 

 the collection, illustrating the method of 

 growth of the shells, and showing all the 

 principal characteristics described in the 

 report, which will be soon issued. 



