ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 877 



penetrate). The sections having heen stained are stuck on with 

 chrome-guin, which is made as follows : — Gum arabic dissolved in 

 water to a thin mucilage, chrome-alum dissolved in water, added in 

 excess to the former; glycerin a considerable quantity; of spirit a 

 small quantity, to render the gum more easily spread on glass. A thin 

 layer of the adhesive is spread on the slide with a brush or with the 

 finger. The paraffin preparations are then laid on and allowed to dry 

 at a temperature of 30°-45° C. Then turpentine, alcohol, or staining 

 with an alcoholic or watery fluid, washing, alcohol, &c. ; balsam. 



Karyokinesis in Arthropods.* — In the study of karyokinesis in 

 the Arthropods, Prof. J. B. Carnoy obtained the best results with the 

 two following mixtures ; — 



(1) (Modified form of Flemming's mixture). Chromic acid (2 per 

 cent, or more), 45 parts ; osmic acid (2 per cent.), 16 j>arts ; glacial 

 acetic acid, 3 parts. (2) Corrosive sublimate ; glacial acetic acid 

 (1 per cent.). The object (testes) is left from one to ten minutes 

 in one of these mixtures ; then washed in distilled waters and further 

 hardened in alcohol. 



Preparing the Mid-gut of Insecta.j — According to Dr. J. Frenzel 

 chromic acid is not suitable for the examination of the intestine of 

 Arthropoda. A mixture of nitric acid and an alcoholic sublimate 

 solution gave satisfactory results. The strength of the alcohol and 

 the amount of sublimate in solution does not appear to matter. 

 The author used 80 per cent, alcohol with sublimate half saturated. 

 No particular caution is necessary as to the amount of acid ; a drop 

 too much or too little doing no damage. To the above solution a 

 drop of concentrated sulphuric acid is added to every one or two 

 cubic centimetres. The presence of this acid induces a quicker 

 penetration of the preservative fluid into the tissues and hinders the 

 formation of insoluble mercurial compounds. The more acid the 

 solution and the smaller the piece of tissue the shorter the time it is 

 left in the fluid. For pieces about the size of a pea five to ten 

 minutes are quite sufficient. After hardening in sublimate, alcohol 

 is advantageous. The tissue is washed and left in 90 per cent, 

 alcohol. 



Methods of Studying the Nervous System of Annelids. I—Macer- 

 ation is the best means of demonstrating the existence of a perijdieral 

 nervous system (Polygordius, Protodrilus, and Saccocirrus), and of 

 showing its relation with the central nervous system. As maceratina- 

 agents, M. J. Fraipont employed weak alcohol (36-48 hours), 

 chromic acid (1/100 per cent., 21 hours), and a weak solution of 

 bichromate of potash (48 hours). 



After treatment with one of these agents, a definite portion of the 



* " La Cvtodie'rese chez les Arthropodes," p. 211 (Extrait de la Revue 'La 

 Cellule,' i., 1885). Cf. Amer. Natural., xx. (1886) p. 578. 



f Arch. f. Mikr. Anat., xxv. (1885) pp. 229-30G (3 pis.). See this Journal, 

 ante, p. 231. 



% Arch, do Biol., v. (1SS4) pp. 251-4. Cf. Whitman's 'Methods in Micro- 

 scopical Anatomy and Embryology,' 1885, pp. 198-9. 



