G32 The American Naturalist. [July, i 
Waldeyer’s Hydrochloric Acid and Palladium Chloride Method!— — 
Small pieces of fixed and hardened tissue are decalcified in a solution 
consisting of: 
Hydrochloric acid 10. parts. 
Palladium chloride..... | ee 
Distilled water ow A O00 eam 
If not softened at the end of 24 hours the solution should be 
renewed ; when decalcified the objects are washed in 70% alcohol 
until the acid is removed. 
Bone Cells.—Chiarugi’s Method’—Small pieces of fresh bone are 
decalcified in picro-nitric acid prepared by adding 2 c.c. nitric acid to 
100 c.c. saturated aqueous solution of picric acid; this solution is then 
diluted with two volumes of distilled water; when decalcified the 
tissue is washed in alcohol of increasing strengths. The sections are 
stained for a few minutes in a 1% eosine solution and decolorized in a — 
3% solution of potassium hydrate. The ground substance becomes 
colorless, while the bone cells and their processes are deeply stained. 
To fix the eosine the sections are washed and mounted in a 1% alum 
solution. 
Fibres of Sharpey.—Kéilliker’s Method.\—The decalcified tissue 
is treated with concentrated acetic acid until transparent, when it is 
transferred to a saturated solution of indigo-carmine for a minute and 
then washed in distilled water; mount in glycerine or Canada balsam 
The fibres of Sharpey are red, the remaining bone substance blue. — 
Lithium carmine and safranin also differentiate the fibres. 
Another method‘ employed is to heat the section in a crucible. The 
calcified fibres are shown with remarkable clearness. 2 
Bone Medulla.—Bizzozero’s Method2—The author, after trying 
many methods, finds the following most useful in studying the elements 
1Arch, f. mikro. Anat., Bd. xi, 1875; Stricker’s Manual of Histology, 18729 
1052. 
*Rollet. della Soc. trai cult. della Scienza Med. Siena. fasc. viii, 1886; Zeit. 
wiss. Mikros., Bd. iv, p. 490, 1888. 
Zeit. f. wiss. Zool., Bd. xliv, p. 644, 1886. 
‘Zeit. f. wiss. Mikros., Bd. iv, p. 87, 1888. 
SAtti della R. Acad. della scienze di Torino, vol. xxv, p. 156; Arch. f. mi 
Anat., Bd. xxxv, p. 424, 1890 ; Zeit. f. wiss. Mikros., Bd. vii, p. 513, 1890. 
