302 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



round the bulb and the ends lie on the metal plates p p, which are also 

 connected with the electrodes. 



Fig. 53 also gives a longitudinal section of the stage ; g g is the cover- 

 glass ujjon or to the under surface of which the object to be examined is 

 fixed. The cover-glass is in contact not only with the surface of the 



Fig. 53. 



slide, but also with the coil of wire surrounding the bulb of the thermometer 

 the transverse section of which is seen at a a. When the circuit is closed the 

 wire becomes heated and acts on the one hand upon the mercury, and on the 



other upon the cover. The 

 hard caoutchouc is a bad 

 conductor of heat, and hence 

 the cover-glass receives the 

 greater part of the heat. 



Fig. 54 shows the 

 Strieker stage as figured 

 in the ' Handbook for the 

 Physiological Laboratory,'* 

 h being the central chamber 

 (surrounded by a copper 

 disc a) warmed by the cur- 

 rent, / a copper plate with 

 a corresponding one on the other side to which the electrodes are applied, 

 c a platinum wire by which the two plates are in communication and which 

 is coiled round the bulb of the thermometer d. 



Dr. S. T. Stein f also uses a platinum spiral (fig. 55) inserted between 



Fig. 55. 



Fig. 56. 



* Burilon-Satiderson, J., E. Klein, M. Foster, and T. Tj. Brunton, ' Handbook for 

 tlic rhysiological Ijaboiutory,' 1873, fig. 14. 

 t Zcitdchr. f. Wias. Mikr., i. (1884) p. IGl. 



