538 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
are those most in use, and it will not be necessary to recount them. 
But it may be useful to give the formulas of solutions made with 
hydrochloric and nitric acids: — Hydrochloric acid, 2*5; alcohol, 500 ; 
distilled water, 100; sodium chloride, 2 5. A variation of the pre- 
ceding is: — Hydrochloric acid, 1-5; alcohol, 70; distilled water, 30; 
sodium chloride, 0*5. These solutions decalcify somewhat slowly, but 
the structural relations of the tissue are well preserved. 
The formula for the nitric acid combination used by the author is : — 
Nitric acid (sp. gr. 1*5-1 *2), 3-9; alcohol, 70; distilled water, 30; 
sodium chloride, 0*25. This solution decalcifies rapidly, but without 
destroying the tissues, and may be used for bone of all ages and densities. 
Its action may be hastened by using an incubator. Preparations stain 
remarkably well after this method. 
Demonstrating Mucin in Tissues.* — From a very thorough examina- 
tion Herr H. Hoyer shows that the mucin in mucous glands of goblet- 
cells of Vertebrata and Invertebrata can only be demonstrated by the 
basic anilin dyes, the acid salts having no effect. The various carmine 
solutions behave like the acid anilins, and the aluminated haematoxylin 
solutions like the basic. 
Double staining with methylen-blue and triamido-benzol, known as 
Bismarck or Yesuvin brown, are found even in dilute solution to impart 
a deep stain very resistant to alcohol; other pigments named as 
giving satisfactory results being methylen-green, dimethylphenylen- 
green, metamidomalachit-green, and safranin. This last produces a 
metachromatic staining of the mucin, imparting thereto an orange 
colour, while the tissue and nuclei are red. 
Another pigment giving excellent results is thionin or Lauth’s violet, 
a derivative of indamin containing sulphur. To the tissue Lauth’s 
violet imparts a bright blue colour, while the mucinous elements are 
red-violet. 
For demonstrating mucin the author treated fresh pieces of tissue 
for two to eight hours with 5 per cent, sublimate solution, and then with 
80 per cent, spirit. After imbedding in paraffin and cutting the tissue, 
the sections, stuck on a slide, were stained with dilute watery solutioi s 
(2 drops of a saturated watery solution of the pigment to 5 ccm. of 
water) for 5 to 15 minutes. Other details relative both to the pigments 
and to the technique are given. 
Preparing and Examining Glandular Epithelium of Insects. - )- — 
Dr. Y. Grandis recommends insects, and especially Hydrophilus, for 
studying glandular epithelium during secretion. After the animal’s 
legs and wing-cases have been removed a cut is made down the whole 
length of the back, and then two others perpendicular to the first, one 
on either side. In making these incisions care must be taken not to 
tear the abdominal air-sacs or the tracheae. The animal is then laid on 
a piece of cork, in the centre of which is a circular hole with a diameter 
of about 1 cm., on the under side of which is cemented a cover-glass, 
* Arch. f. Mikr. Anat., xxxvi. (1890) pp. 310-74. See Zeitsckr. f. Wiss. Mikr., 
viii. (1891) pp. 67-70. 
t Atti R. Accad. Sci. Torino, xxv. (1890) pp. 765-89 (8 pis.). See Zeitschr. f. 
Wiss. Mikr., viii. (1891) pp. 86-7. 
