ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 555 



axis cylinders of the sensory nerves. These blue-tinged axis cylinders 

 were found very numerously in the gustatory cuplets, at the bases of 

 which they formed a quite narrow reticular network, whence, single 

 fibres ending in knots proceeded anteriorly to the ciliated cells. Net- 

 works of blue fibres were found very copiously and closely in the 

 cornea. The iris likewise showed blue plexuses, particularly on the 

 anterior side ; on the posterior side only long cancellated reticula were 

 observed. In the muscles, on the other hand, were found only detached 

 blue fibres, the ending of which in the muscle-fibre could not be 

 established. The axis cylinders of the motor nerves were, according 

 to this experiment, not coloured by methyl-blue during life ; it was 

 only the sensory nerves which reacted to the colouring matter. The 

 vessels, arteries, capillaries, and veins were surrounded by blue 

 plexuses. It could not, however, be decided whether the blue fibres 

 proceeded to the smooth muscle-cells. In the retina the nervous layer 

 showed no blue colouring. In the ganglion layer, on the other hand, 

 cells richly charged with blue, and having numerous branching pro- 

 cesses, were found, which, too, were in communication with the pro- 

 cesses of neighbouring cells. In the mixed nerve-stems and in the 

 roots of the nerves no blue fibres were found. The central ends, on the 

 other hand, showed a decided methyl-blue reaction, as did also the peri- 

 pheral ends of the sensory nerves. In the brain, blue fibres were 

 found only rarely, but were very abundant in the medulla oblongata, 

 while they were wanting, again, in the spinal marrow, and from these 

 results it appears that the colouring of living organs with methyl- 

 blue is a very important means of observing the endings of sensory 

 nerves in them. 



It must, however, be borne in mind, that the examinations had to 

 be prosecuted very rapidly after the colouring process, because, in 

 living tissue, the colouring material was lost by diffusion very quickly 

 — in the course of a few minutes — and the colouring of the axis 

 cylinders disappeared. 



Staining the Nervous System of the Muzzle and Tipper Lip of 

 the Ox.* — Dr. J. Cybulsky recommends the following method : — 



Fresh pieces of the epidermis with a thin layer of the corium are 

 imbedded in elder-pith, and cut with a knife wetted with alcohol and 

 water. The sections are placed for a quarter to three-quarters of an 

 hour in a weak solution of chloride of gold, washed with distilled 

 water and placed in a hermetically sealed vessel in a solution of 

 tartaric acid (saturated or diluted to 1/2). This is placed in water 

 warmed to 50^-60°. Already, in a quarter of an hour, a bright red or 

 bluish striation appears in the sections in consequence of the reduction. 

 The proper degree of staining can only be learnt by experience. If 

 the reduction is continued for a long time the acid must be renewed. 



Employment of Colouring Matters in the Study of Living In- 

 fusoria.t — M. A. Certes finds that dahlia, chrysoidin, nigrosin, methyl- 

 blue and iodine-green have the property in different degrees of colour- 



* Zeitschr. f. Wisa. Zool., xxxix. (1883) pp. 653-82. 

 t CE. Soc. de Biologie, April 5th, 1885. 



