ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
827 
(2) Preparing- Objects. 
Preserving Fluid.* * * § — Prof. Sfcrobel strongly recommends “ il liquido 
Caggiati ” as a preserving medium for entire animals and for anatomical 
preparations. Though it cannot be used in extremes of beat or cold, it 
is otherwise most advantageous ; it is economical and simple, is not 
inflammable, and does not remove the colour of the objects preserved. 
Its composition in cubic centimetres is distilled water 1000, creosote 20, 
alcohol (at 75) 100 parts. 
Investigation of Fowl’s Ovum.t — Prof. M. Holl removed the ovary 
from a just killed hen, and fixed it either with chrom-osmium-acetic 
acid or 1/3 platinum chloride or Kleinenberg’s fluid. After gradual 
hardening in alcohol, staining was effected with borax-carmine or 
haematoxylin, and after treatment with toluol, imbedding in paraffin 
followed. 
Preparation of Embryos of Amphibia.^ — Mr. H. H. Field, in his 
investigations into the development of the pronephros and segmental 
duct of Amphibians, made use of the ordinary histological methods ; 
many, however, of the hardening reagents and stains gave thoroughly 
unsatisfactory results. Embryos of Bana and Bufo can be satisfactorily 
killed in Kleinenberg’s picrosulphuric mixture, and can be then success- 
fully stained in Orth’s lithium-carmine. The object should be exposed 
to the action of the stain as long as possible, but care must be taken to 
guard against maceration ; with this object it was often found advan- 
tageous to stain the object twice, removing it after the first staining to 
strong alcohol. In passing the stained objects through grades of alcohol 
it is important to keep a little picric acid dissolved in the several fluids, 
in order to prevent the alcohol from extracting the yellow stain from 
the specimen. Embryos thus treated showed a very effective double 
stain ; the nuclei are bright carmine, and contrast with the yellow colour 
imparted by the picric acid to the yolk-spherules among which they are 
found. Merkel’s fluid is a good killing reagent, and should be followed 
by haematoxylin, and the decolorizing watched with care. 
For Amblystoma the best treatment was Fol’s chromic-osmic-acetic 
mixture, followed by Czokor’s cochineal. 
Investigation of Brain and Olfactory Organ of Triton and Ichthy- 
ophis.§ — Dr. R. Burchhardt recommends for young Amphibian larvae 
which still contain a considerable quantity of yolk, preservation in 
Rabl’s fluid, and coloration with borax-carmine or alum-cochineal. 
For older larvae Rabl’s fluid, Altmann’s process for chrom-acetic acid 
(1 per cent, chromic acid 10 hours, 5 per cent, acetic acid 24 hours, 
alcohol in slowly increasing quantities, and then 1/2 per cent, osmic 
acid for 5 hours). The preparations should be washed in water and 
stained with borax-carmine or Delafield’s haematoxylin. Specially exact 
results were obtained by fixing with osmic acid and staining with 
haematoxylin. Excellent results are also to be obtained by the com- 
bination of borax-carmine with nigrosin or Lyon’s blue in a weak 
* Neptunia, i. (1891) pp. 301-2. 
t SB. K. Akad. Wiss. Wien, xcix. (1890) p. 369. 
X Bull. Mus. Comp. Zool., xxi. (1891) p. 203. 
§ Zeitschr. f. Wiss. Zool., lii. (1891) p. 370. 
3 M 2 
