February, 1907.] 



KNOWLEDGE & SCIENTIFIC NEWS. 



47 



short time, and tlicn cooling to a gentle warmth, 3 

 c. cm. of a 2 per cent, solution of malachite green are 

 addetl. ^^■hen this medium is inoculated with typhoid 

 bacilli, and with other organisms belonging to the 

 typhoid family, striking differences are brought out- 

 In the typhoid tubes, the nutro.se is precipitated in a 

 qLiite distinctive manner. The fluid is coagulated like 

 acidified milk, and alcove the coagulated layer there is 

 a clear, green liquid. With the majority of the other 

 organisms, such as the Coli group, Gaertner's bacillus, 

 and paratyphoid bacilli, active fermentation takes place, 

 the precipitated nutrose adheres to the walls of the 

 tube as dirty, green flakes, whilst some of it is carried 

 to the surface by the gas formed, and floats as a dirty 

 green layer. When grape sugar is omitted from the 

 medium, only the Coli group cause fermentation, and 

 they can, therefore, be differentiated from the rest, 

 whilst other organisms have a reducing action on the 

 green, turning it a pale yellow, more especially when 

 the alkalinity of the medium is slightly increased. The 

 typhoid bacillus does not change the medium, but only 

 exerts a very gradual reducing action on the green. 

 The paratyphoid bacillus .\, on the other hand, turns 

 (he solution pale blue. 



Journal of the Quekctt Club. 

 The last (NoAember) issue of the Journal of the 

 Quekctt Microscopical Club is in no way inferior to its 

 predecessors, and contains, amongst much other matter, 

 some most interesting notes and observations on the 

 life-history of fresh-water mites, by Mr. C. D. Soar, 

 from the cg^ to the larval, nymph, and adult stages ; 

 an illustrated paper by Mr. "Julius Rheinberg, on 

 " Stereoscopic Effect and a Suggested Improvement in 

 Rinocular Microscopes ; " and a lucid account by Mr. 

 D. J. Scourfield, of Mendel's " Law of Heredity," with 

 special reference to its relation to microscopy, which 

 any who are interested in this fascinating subject, but 

 have had little opportunity of studying it at first hand, 

 should read. The Laws of Mendel are very nrominent 

 just now amongst biologists, and have an important 

 relation, not only to our conceptions of evolution and 

 variation, but to many practical problems in economic 

 botany and geology which the general public will 

 realise with surprise when they are accomplished com- 

 mercial facts. There are the usual reviews, once more 

 restored to the Journal, reports of the Proceedings of 

 the Club, and a list of members and office-bearers, 

 together with some excellent plates and illustrations. 

 Microscopical Material. 

 Mr. J. Strachan, (if Hallyclare, has \ery kindly sent 

 me for distribution, some microscopic crystals of lead 

 chloride (Pb CI2). Mr. Strachan says : " The crystals 

 h;ive taken several months to grow, rnd are in the form 

 of rhombic plates, the usual form being that of rhombic 

 needles. They contain numerous cavities, similar to 

 tho.se found in certain rock-forming minerals. There 

 are also numerous undeveloped crystals, so-called 

 ' crystal-eggs.' I find that Canada balsam is a ycry 

 suitable mounting nv.-diuni for crystals." I shall be 

 glad to .send some of these crystals tO' any reader who 

 caras to .send me a stampi'd addres.sed envelope, a small 

 tin box (they are easily crushed'), and the coupon to be 

 found in the advertisement columns of this issue of 

 " KNOWi.ivDr.F.," but I must warn applicants that the 

 amount of material is \iry small, and they will only 

 receive a very small quantity accordingly. 



Notes and Queries. 



Qiiilitt ^firriiscnpiiiil Cliih. Mr. Mmlaiul, h;iving given 

 in> Ihi' iKisI of IIiMior.ux li-r.-i^urcr lo llic (Jurkrll Ckib, the 



Committee have appointed Mr. Frederick J. Perks, of 48, 

 Grove Park, Denmark Hill, S.E., as Treasurer in his place 

 as from January i, igoy. All subscriptions and other pay- 

 ments, together with notices of change of address, should, 

 therefore, for the future be sent to Mr. Perks, as above. 



C. J. I). (Hatjwar(Vs Heath). — I cannot lay claim to any 

 special legal knowledge, but I do not see how there can be 

 any copyright in microscopic slides as such. It would be as 

 reasonable to suggest that there is a copyright in a stuffed 

 animal. Therefore, there can be no reason why you should 

 not photograph or draw any slide you like, whether pur- 

 chased or not, provided it is your own, failinsj which it 

 would, of course, be at least courteous to ask the owner's 

 permission to do so. Having photogi^raphed it, the usual laws 

 of copyright will apply to the photograph or to the drawing 

 when published. 



F. R. H. S. (Munirh). — It would be impossible to say 

 whether the times recommended in any book on Human 

 Histology for fixing animal tissues are equally applicable 

 to vegetable tissues, without knowing what fixatives and 

 what materials are referred to. Generally speaking, a book 

 on Human Histology would be a very unsatisfactor)- guide 

 to the preparation of vegetable structure. There are so 

 many modifications, but in nearly all cases the most fre- 

 quent causes of f.ailure are insufficient time in fixation and 

 insufficient washini^ afterwards. It would be better for you 

 to |)rovide yourself with some well-known practical text- 

 book, like .Strasbursjer's " Das Botanische Praktikuni." 



T. H. H[. (Hnr/ley). — Vou will find very full instructions for 

 the collecting and preparing; of foraminifera in " Know- 

 ledge " for January and February, iqo2, in a couple of 

 articles written bv Mr. .\. Earland. Briefly sunimari.sed, it 

 is necessary to wash and sort the material before proceeding 

 to mount it. The material distributed last month has been 

 already washed, but it will be convenient to pass it through 

 gauze wire of various meshes. Mr. Earland recommends 

 two sieves 40 and 120 meshes to the inch, the diameter of 

 the apertures in the latter being about 3iii of an inch. It is 

 necessary to " float " and " rock " the material. The 

 " floating " is done in bright daylight, t|ie material being 

 slowly poured into a jar of water. The sand sinks most 

 readiiv, and the more slowly following foraminifera are 

 then rapidly tilted over and through the finest sieve. By 

 this means the material is roughly sorted. The " floating " 

 is best done in a phototjraphic developing dish, the residuum 

 being placed in this for a depth of .ibout a qu;irter of .an 

 inch and covered with about three-quarters of an inch of 

 water. By rocking and circular movements the foramini- 

 fera are suspended in the water and manipulated into one 

 corner of the di.sh, whence they are suddenly tilted into 

 the sieve. The material must then be dried, and the 

 foraminifera selected under the microscope, for which pur- 

 pose Mr. Earland recommends a little shallow tray covered 

 with coarse black-ribbed silk to keep the for.iminifera from 

 rolling about, the specimens beinir selected Iw means of a 

 fine sable brush moistened with the lips, and then transferred 

 to a prepared cell or slip. 



.\s fixative for mounting, Mr. Earland recommends gum 

 tragacanth, which is almost invisible when dry, and free 

 from the objectionable glaze of gum arable, and also less 

 subject to variations of moisture in the air. He adds that 

 the same gum, diluted to a watery consistency, can be 

 u.sed as a fixative for foraminifera before mounting in 

 balsam, the gum, which must be thoroutjhlv dried, being 

 quite invisible in b.ilsam. Dry mounts can be m.ade in a 

 similar way, the foraminifera beintj mounted between two 

 cover-glasses, the lower one beintr blackened before lieintj 

 fastened to the slide, and the whole ringed round in the 

 usual way. My own method is to mount all opaque ob- 

 jects with tr.-msparent backgrounds, and to have one or two 

 plain slides with circular discs of dull black paper fastened 

 on them which I can place behind the slides when I wish to 

 illuminate them as ojiaque objects. By these means obiects 

 such as foraminifera, mounted dry, can bi' illuminated from 

 above ;is opaque objects, or from below with annular (dark- 

 groimd) illumination, as required. 



[CommiinicalioiK and inquirits "» Micrtscot-iciit niiilttn shoii'ii h' 

 addressed to F. Sliillington Siiiles, " Jersty." St ftarniihis Road, 

 Canihridse. Cfrrrsf'ondfnt^ are requested not to se'id stecw'etis to fr' 



iuimed .\ 



