ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 733 



separate. Care should be taken to support one side of the cover by 

 a hair, which is removed quite gradually, after the object has been 

 reduced to very small cell-masses. Sliding of the cover may be 

 avoided by placing wax feet under its corners. 



Dr. Mark has employed this method, and obtained excellent 

 results with it. As he remarks, the great merit of this fluid is, 

 that it separates the cell-elements and hardens them at the same 

 time. The dissociative and the preservative agent are combined in 

 such proportions, that the action of the former is confined within 

 desired limits by that of the latter. 



Blue Stain.* — T. F. Hazel wood, using the carmine stain of Dr. 

 Seller, but not satisfied with the diflerentiation of the single stain, 

 found a blue stain composed of rosanilin, anilin oil, and sulphuric 

 acid, which gives the finest demonstration of tissues he has ever seen, 

 for while the carmine gives the nuclei, the blue will give the outlines 

 of the cells, fibrillae of muscles and nerves, connective tissue fibres, 

 &c. Several tongues of frogs, which had been stained with carmine 

 and mounted in glycerine and acetic acid, after Beale, and left for 

 nearly two years sealed up in glycerine, were taken out of their cells 

 and put through the blue stain, and then mounted, each tongue in a 

 series of slides, with glycerine as the medium. A magnificent de- 

 monstration of simple and compound papillae was the result, with the 

 branched muscle-fibres and delicate nerves in situ, also nerve-trunks 

 and ganglion cells. 



The skin of the frog has, by the use of this same double stain, 

 furnished another means of studying the arrangement of the nerves. 

 Even the most delicate nerve-fibres are thus brought out with great 

 distinctness. In vertical sections of nerve-trunks, by this treatment, 

 the outline of the individual sheaths is distinctly seen, with the axis- 

 cylinder in the centre. So great is the change wrought by this blue 

 stain that the author has dismounted many of his slides and put them 

 through this process, and then remounted in balsam or glycerine at 

 pleasure. 



The stain gives equally surprising results in differentiating the 

 tissues of insects. Nerves and tracheae and cell-walls are finely 

 coloured. The fine network of muscles and nerves on the stomach 

 and intestines and on the glands is thus brought out with stereoscopic 

 effect. 



In the case of the muscles of the Lampyridae the accessory disks 

 of Engelmann can be distinctly seen. The nerves and ganglia in the 

 thin membrane of the bat's wing are also well brought out. 



Lelong's Microtome. t — M. Lelong's apparatus, fig. 151, consists of 

 two vertical plates A, having a space between them partly occupied 

 by an inclined plane on which slides a piece B containing the object 

 to be cut, which is put in the cavity C, where it is kept in place by 

 the screw D, which by pushing forward or withdrawing the piece E, 



* Amer. Mon. Micr. Journ., iv. (1883) pp. 109-10. 



t Latteux, P., ' Manuel de technique microscopique,' 2nd ed., 1883, p. 41 

 (1 fig.). 



Ber. 2.— Vol. Ill- 3 



