$2 PRACTICAL HISTOLOGY. 



cannot cut all tissues with equal rapidity. In the case of many 

 tissues and organs (as elastic tissue, lung, kidney, &c.), after they 

 are completely frozen, a quarter of an hour will suffice, if a planing 

 iron be employed, to cut more than a thousand sections. This, 

 however, cannot be done with sections of the cerebrum, cerebellum, 

 or spinal cord. With these and with some other organs it is 

 better to cut each section singly. 



I'IG. 34. CaMicart's Freezing Microtome. 



If one has several tissues to cut, the one tissue can be embedded 

 above the other in the instrument at the same time. 



This instrument, however, has other advantages, as it can bo 

 used also as an ether-freezing microtome. Place the tissue, 

 previously saturated with the freezing fluid, upon the zinc plate 

 Z, and cover it with mucilage. By means of an ether-spray 

 producer N, direct a spray of anhydrous ether from the bottle 

 against the under surface of the zinc plate Z. 



In order to economise ether, any non-volatilised is collected 

 and returned by the tube T to the bottle 0. 



