ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 853 



recommended for preserving the coloured parts of plants, as the dyes 

 are given off after the lapse of a few months. 



The author then discusses the brittleness which affects plants which 

 have been long kept in strong spirit. This brittleness may be prevented 

 by soaking the parts in water until they become quite flaccid and then 

 placing them in spirit. As the results of his examination into the cause 

 of this brittleness, the author finds that when the tinged parts of a plant 

 are killed by immersion in spirit, their death is effected before the 

 tension of different parts has had time to become equalized. Hence this 

 tension is " fixed " by the sj)irit and becomes the cause of the brittleness. 

 Water, however, equalizes the tension of the various parts, and hence 

 removes the brittleness by rendering the tissue elastic. 



Fixing Sections to the Slide. * — Mayer's albumen fixative, says 

 Mr. J. Nelson, is absolutely reliable for fixing sections to the slide, and 

 should be used whenever sections are loosely coherent in their parts. 

 Neat results with this can only be obtained with a very thin and even 

 film, to secure which proceed as follows : — A small drop of the fixative 

 is spread on the slide with the ball of the index finger. Excess of 

 fixative is removed by wiping the finger dry, and continuing the rubbing 

 until no frothy streaks appear in the film. Then tap the moist surface 

 lightly with the finger, so that by light reflected at a proper angle it 

 appears finely stipj)led. Each section is pressed into the film with a 

 brush, and when the slide is full, a piece of filter paper is placed over 

 all, and pressed firmly with the finger until every part of each section is 

 in even contact with the glass. Then heat the slide over steam until 

 the paraffin melts, and then plunge into turpentine. The film is opaque 

 in alcohol, but this is corrected in turpentine and mounting. Should 

 the presence of the foreign albumen in the sections be undesirable, 

 recourse should be had to Gaule's alcoholic fixative. It is a means 

 whereby the albumen molecules of the section are brought into the same 

 adhesive contact with the glass as those of ordinary fixatives. The 

 slide is brushed over with 40-70 per cent, spirit, and when this film has 

 evaporated, thin sections stick closely. Superfluous spirit is removed 

 with bibulous paper, and the slide then evaporated to dryness ; this is 

 best done in a thermostat at 40^ C. for 1-2 hours. The paraffin should 

 never be allowed to melt. It is removed with turpentine as for other 

 fixatives. Celloidin sections stick well with this method. 



VoiNOFF, R. G. — On tlie different Cements for closing microscopical sections. 



Ejened. Klin. Gaz. St. Petersburg, VII. (1887) p. 411 (Russian). 



WoJNOFF, K. — Einige Bemerkungen betreffend das Festkleben mikroskopisclier 

 Schnitte anf Objecttrager. (Some remarks on fixing microscopical sections to 

 the slide.) Klin. Wochenschr., 1887, 6 pp. 



C6) Miscellaneous. 

 Methods of Plastic Reconstructioii.t — Prof. H. Strasser writes at 

 great length and in copious detail on methods of reconstructing the 

 object. All he has to say is practically a recapitulation of Bern's 

 procedure for making wax plates upon which the image of the object is 

 drawn. The outline is then cut out, and the various plates are united 

 together in their proper order, and this done the edges are smoothed off 

 so that an enlarged solid copy of the original object is obtained. For 



* American Naturalist, xxii. (1888) p. 664. 

 t Zeitschr. f. Wiss. Mikr.,iv. (1887) pp. 168-209, 330-9. 

 1888. 3 M 



