ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



389 



are stirred together with a glass rod, and the mixture having been 

 covered with a slip, is observed under the Microscope. 



The fresher the heterologous blood, and the more concentrated the 

 solution, the more rapid is the reaction. 



Permanent preparations showing the reaction may be made in the 

 usual way. 



Apparatus for Making Wax Plates for Reconstruction Models.* — 

 A. Fleischmann uses a smooth cast-iron plate (<><) by 90 cm.), levelled by 

 means of adjusting screws as a surface for rolling out wax 

 plates. The roller is 50 cm. long, and 4 cm. in diameter, 

 and is made of steel. A circular disc is inserted between 

 the handles and each end of the roller for the purpose of 

 regulating the thickness of the plate. This device is far 

 more effective than placing strips of glass or metal on the 

 table. 



Needle for obtaining Blood for Examination.! — J. Pies 

 describes a needle which he has invented for the purpose 

 of pricking the skin to obtain blood for microscopical and 

 other examinations. As will be seen from the illustration 

 (fig. 73), the head, which is perforated for the reception 

 of the needle, is actuated by a spring. The needle is fixed 

 by a screw, the head of which is pressed into the side 

 groove. By exerting slight pressure on the knob the spring 

 is released, and a rapid and painless incision made in the 

 skin. The upper end of the case serves to keep spare 

 needles in. 



Fig. 73. 



Examining Caoutchouc by the Aid of the Microscope.^ 

 P. Breuil examines caoutchouc by reflected and by trans- 

 mitted light, by the aid of a Microscope which is also fitted 

 up for photographing the preparations. Thin films are 

 obtained by evaporating solutions of caoutchouc in divers 

 solvents. Delicate transparent strips may also be used. For 

 examining with reflected light, an arc light of 20 amperes 

 is necessary, and the specimens used are prepared after the 

 manner used in metallography, i.e. the pieces are shaped, 

 polished, and etched with sulphuric and nitric acids. Microscopical 

 inspection enables the observer to detect the nature and purity of the 

 rubber, as well as the presence of impurities and adjuvants. 



Schapkr, A. — Eine Methode zur Durchschneidung grober Wachsplatten Modelle.) 

 (Method for cutting through large wax plates by means of a thin metal wire 

 heated bv the electric current.) Zeitschr. wiss. Mikrosk., xxi. (1904) 



pp. 200-6 (4 figs.). 



• Zeitschr. wiss. Mikrosk., xxi. (1904) pp. 479-80 (2 figs.). 



+ Tom. cit., pp. 445-6 (1 fig.) 



t Comptes Rendus, cxl., (1905) pp. 1142-3. 



