ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
Ill 
Demonstrating the Neiirokeratin Network of Nerve-fibres.* — 
Dr. G. Plainer advises the following procedure for demonstrating the 
neurokeratin network. 
Thin fresh pieces of nerve, freed from connective tissue and fat, are 
placed in the following solution — Liquor ferri perchloridi 1 part, 
distilled water or rectified spirit 3-4 parts. In this the pieces of nerve 
are left for days to weeks. The iron chloride is then to be thoroughly 
washed out so that no trace of iron can be chemically detected in the 
water or spirit. After this the pieces are to be kept till wanted in 
spirit. 
The best stains for nerves thus manipulated are “ Echtgriin,” a 
dinitroresorcin which in combination with the iron still remaining in 
the tissues gives a green colour, and alizarin, which imparts a deep violet 
hue. 
To use dinitroresorcin, a supersaturated solution of the solid pigment 
is made in 75 per cent, alcohol. In this solution large pieces of tissue 
require to lie for several weeks. When thoroughly freed from iron the 
immersed pieces gradually become dark green, but the fluid itself exhibits 
no trace of green. After having been dehydrated, the pieces are im- 
bedded, and sections, both longitudinal and transverse, made. In 
transverse section, the axis cylinder is stained a dark emerald green, and 
from this radiate outwards to the medullary sheath, numerous green 
delicate filaments, the neurokeratin network. In longitudinal section 
the same network is shown. 
The stain is fairly resistant to acid and alkaline reagents, and the 
different methods of hardening do not exclude the use of the perchloride 
solution. 
Preparing the Silk-glands of Araneida.f — Dr. 0. Apstein, in 
making a macroscopical examination of the living animal, opened the 
body under water and then removed the heart, intestine, liver, and organs 
of generation. An addition of some drops of sublimate to the water 
imparted to the previously glass-like spinning-glands a milky appearance. 
Alcohol-material was prepared under 35 per cent, spirit. For sectioning 
the author prepared the animals with hot water, boiling them from 1/2-3 
minutes, according to size, and then imbedding in paraffin, after j^assing 
them through turpentine or chloroform. The author cautions against 
using cedar-oil, as it is a poor solvent of paraffin. Borax-carmine, and 
after-staining with liaBmatoxylin, are recommended for staining. 
The statement that the silk-threads of the glandulae j^yriformes 
consist of a double substance is interesting, since the secretion from the 
upper part of the gland forms a solid non-staining cord, while the cells 
from the lower parts of the glands secrete a tubular filament which is 
clearly stained. The author verified this in different species. 
Preserving Actiniae. J — Dr. J. P. M‘Murrich recommends the 
collector of Actinians who has not the time to properly carry out the 
narcotizing methods to act as follows. After noting general character- 
istics, place the animal in a jar just wide enough to allow of its complete 
* Zeitschv. f. Wiss. Mikr., vi. (1889) pp. 186-8. 
t Iiiaugural-Dissert. Kiel, 1889. Cf. Zeitschr. f. Wiss, Mikr., vi. (1889) pp. 199-200. 
j Journal of Morphology, iii. (1889) pp, 2-3. 
