ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 



305 



conductor,* while Sig. Koritsha of Milan makes the ends of the arms B 

 terminate in discs, to give an extended heating surface. 



Prof. Strieker's first form f consisted of a copper ring or rod inserted 

 into a glass slide so as not to project beyond the surface. A second rod 

 with a spiral coil is slipped over the free end of the first rod, and its 

 extremity heated by a spirit-lamp. This has been further simplified t hy 

 making the ring and rod in one piece, as shown in fig. 60. 



Fig. 60. 



Two simple modifications of this form are also shown in figs. 61, 62, 

 and 63. 



The first § (figs. 61 and 62) has an oblong copper plate 2x1 in., 

 from one side of which projects an arm of the same metal 4 or 5 in. long. 

 The plate has a round aperture in the centre 1/2 in. in diameter, and 

 is fastened to an ordinary slide by sealing-wax. The rod is heated near 



Fig. 61. 



its end by a small spirit-lamp as shown in fig. 62, and the heat is conducted 

 by the rod to the copper plate, and from this to the preparation. If an 

 object is under examination, such as white blood-corpuscles, which it is 

 desired to warm to about the temperature of the body, a small fragment 

 of a mixture of white wax and cacao butter melted at about 30° C, should 

 be placed upon the copper (fig. 62). The lamp is now gradually approached 

 along the rod until it arrives at a point, the heat transmitted from which 

 is just sufficient to partially melt the fragment, and it is then left burning 

 at that spot. 



The other form (fig. 63) consists of a square copper plate b with 

 a central opening c. A rod e projects from its under surface (upper as 



* Beale's ' How to work with the Microscope,' 5th ed., 1880, p. 189. 



t Op. cit., pp. xvii.-xviii. (1 fig.). J Burdon-Sanderson, op. cit., pp. 6-7 (1 fig.). 



§ Schafer, E. A., ' A Course of Practical Histology,' 1877, pp. 18-20 (2 figs.). 



