148 



PRACTICAL HISTOLOGY. 



ing small objects at a constant temperature. Strieker 

 and Sanderson have described a larger stage, whereby such 

 an object as the omentum of the guinea-pig may be kept 



FIG. 50. Schaefer's apparatus for heating warm stage. 



at a constant temperature for the study of the circulation. 

 (See Quarterly Microscop. Journ. , Oct. 1870.) 



263. Application of Electricity. Various compli- 

 cated arrangements have been devised for the transmission 

 of electricity through microscopic objects. The following 

 simple arrangements, however, answer the purpose perfectly. 

 Take a slip of glass 1x5 inches, and of the thickness of an 



FIG. 51. Gold-leaf electrodes. 



ordinary slide.* Cover one surface with a thin layer of 

 gum-arabic or gold size; press the moist surface firmly 

 down on gold-leaf; allow it to dry; scrape away the gold- 

 leaf, so as to leave two triangles, e e (Fig. 51), with their 



* An ordinary slide might be used for these electrodes, but it is 

 convenient to have the slide so long that its ends project beyond the 

 stage. 



