ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 885 



leave fur fifteen minutes more. Then the water may be poured off, 

 and the mounting-fluid, whether glycerine, carbolic-acid, gelatine, 

 Goadby's or Thwaites' fluid, may be added. The object, if mounted in 

 any of these, will have a far more natural appearance, and show more 

 plainly the finer structures, than if mounted in Canada balsam. The 

 times mentioned above are those it is necessary in most cases to wait, 

 but longer intervals would often be preferable. If we are busy the 

 tube and its contents may be left at any stage of the proceedings for 

 days, with a certainty that the object will only benefit by the delay, 

 except in the case of the soda-solution. It is not necessary to use 

 distilled water, though it is better to do so ; but whatever water is 

 used, it should be just freshly boiled and be used hot. Cold unboiled 

 water contains a large quantity of air, and if used in that state will 

 certainly impart air to the object instead of helping to extract it. 



The soda or potash solution is made by adding solid potash or 

 soda to eight times its weight of boiling water, and the only expense 

 of the process is for the tube, soda, alcohol, and ether — a pint of each 

 of the latter will prepare some thousands of specimens. 



The same system will answer for sections of wood, small seed- 

 vessels, leaves, &c, only they must first be decoloured by pouring 

 sodic hypochlorite into the tube, then, after well washing with water, 

 the rest of the process may be followed as before, leaving out entirely 

 the use of the soda-solution. The great difference is in the matter of 

 speed, vegetable preparations being made far more rapidly. It is 

 possible to cut a dozen sections from a living branch, bleach, stain, 

 and mount them in Canada balsam or glycerine-solution, and finally, 

 ring and label them, all within the hour. 



Should any of the preparations — the blow-fly's head, for instance 

 — become too colourless and transparent, all we have to do is to stain 

 them by the addition of a few drops of an alcoholic solution of some 

 colouring matter (logwood answers well) to the alcohol in the tube. 

 The subsequent use of ether will fix the colour. 



Usually, after this treatment, the object will be found to be quite 

 clean ; but if not, it should be gently brushed with a camel-hair 

 pencil while in the turpentine or glycerine fluid. The wings of many 

 insects are partially destroyed during the process, but since these can, 

 if desired, be easily mounted separately, this is not of very great 

 importance. 



Directions are also given for mounting the object as above prepared 

 in cells, the use of vulcanite rings being recommended. 



Staining with Magdala-red-* — Dr. C. Norner refers to the 

 fact that picrocarmine (Kanvier's) affects different classes of 

 animals very differently. Tape-worms, for example, redden very 

 quickly, while other worms, like the Nematodes, take very gradually 

 a yellowish tinge, because in their case the picric acid takes effect 

 first and the carmine only after a longer time. Mites are also affected 

 variously — some become yellow, others red, and others perhaps 

 remain colourless. Magdala-red is not open to these objections, and 



* Arch. f. Mikr. Anat., xxi. (1882) pp. 354-5. 



