Miscellaneous. 155 



PRESERVATION OF PREPARATIONS FOR THE MICROSCOPE. 



One of the greatest obstacles in the study of plants — in cases, at 

 least, where the aid of the microscope is indispensable — is the diffi- 

 culty of preserving the minute parts and sections which have formed 

 the materials of observation, and which require to be compared again 

 and again, before complete conviction as to the certainty of any par- 

 ticular facts can be obtained. Every one who has attempted to dive 

 into the intimate structure of vegetables, knows how hard it is to 

 make useful sections, and that it is often practically impossible to 

 obtain a second of equal excellence with one which a nappy direction 

 of the knife has once achieved. An easy method, therefore, of pre- 

 serving such preparations would be invaluable. It is true that the 

 plan adopted by Mr. Thwaites and others with such success, is avail- 

 able for a very large class of objects, but there is much difficulty in 

 preparing both the cells and fluid in which they are to be preserved ; 

 and after all, not only is the expense considerable, and the necessity 

 of keeping a large quantity of very brittle objects in a separate cabinet, 

 with a very strict system of labelling, if the collection is to be of any 

 real value, an unavoidable waste of much time, but after all, even in 

 the best hands, the varnish is apt, after some months, to get into the 

 cells and destroy the delicate specimens. Besides which, objects so 

 mounted are, in consequence of the thickness of the cells, of no use 

 for the microscopes called doublets. 



A very easy and compendious method of preserving all such pre- 

 parations as readily imbibe water has lately been proposed by C. 

 Miiller, which bids fair to be of great value. Slices of the very best 

 and most translucent talc are cut of any convenient size, and made so 

 thin that they will admit of being easily divided with a fine pointed 

 penknife. The lamina is then to be slit to the middle, and the object 

 inserted in the fissure with a little water. It will be found convenient 

 if possible to make the fissure nearer to one surface than the other, 

 and to mark the divided end by cutting off the corners. With a little 

 practice it will be found that the division will always be effected in 

 such a way as to secure the cohesion of the two laminae, and the re- 

 tention of the object. When the objects are wanted for the micro- 

 scope it will be necessary merely to dip the marked end of the talc 

 in water, with a pair of pincers ; and by means of capillary attraction, 

 the object will at once be properly moistened. A slip of paper neatly 

 gummed upon the undivided end, will at once answer the purpose of a 

 label, and will point out the upper surface of the talc, a matter of 

 some importance where deep doublets are used, supposing the lower 

 division of the plate to be thicker than the upper. It is clear that 

 objects so preserved may be kept between the same sheets as the spe- 

 cimens from which they are taken, and will therefore be immediately 

 accessible without any loss of time. In a collection of Mosses, for 

 instance, and Jungermannise, especially where the specimens are small 

 and unique, and where in consequence it is often impossible to examine 

 the peristome more than once, unless the preparation can be preserved, 

 we have an admirable method of making even the rarest individuals 

 available for future observation. 



The same method will apply to the greater part of fungi and other 



