Application of Nigrosine to the Study of the Salivary Chromosomes

Abstract

IN this work, an alcohol-soluble nigrosine (Edward Gurr) was used, and the stain prepared by Rosen's method^1,2. The scheme of treatment followed for staining the salivary chromosomes of Drosophila is as follows. (1) Dissection in 45 per cent acetic acid. (2) Treatment with freshly prepared alcoholic hydrochloric acid during 1–2 min., keeping the glands well covered. (3) The specimen is washed two or three times carefully with distilled water, and a big drop of water is left on the material for 5 min. (4) Drain thoroughly and carefully. (5) Add a drop of stain and put on a cover slip, without squashing. (6) After 10–15 min., squash under blotting paper and immediately put a big drop of glycerine on one edge of the cover slip. (7) The preparation can be studied at once; but after 24 hr., the glycerine having penetrated the specimen thoroughly, it is convenient to get rid of excess liquid and make a wax border. Preparations thus obtained last a long time if handled carefully.