1882-83.] 



Edinb2trgh Naturalists Field Club. 



113 



tissue to be cut, but also to reduce the instrument itself to a cor- 

 responding temperature. In the Cathcart microtome only those 

 parts which it is essential should be cooled are reduced in tempera- 

 ture, the results of this being that a saving is effected in the 

 amount of ether used, and at the same time freezing is quickly 

 effected. The instrument consists essentially of two parts, which 

 are shown in figs. 1 and 2. Fig. 1 is a perspective view of the 

 microtome, with all the parts shown except the spray-bellows. 

 Fig. 2 is a sectional view of the ether points which are shown in 

 position at E in fig. 1. It will be seen that the upper tube of E is 



Fig. 1. 



connected with the bottle J, in which the ether is contained, while 

 the under tube of E communicates with the rubber-tube L, which 

 is led to the spray-bellows, not shown in the figure. When the 



A 



CI 



B 



<? 



Fio. 2. 



bellows are worked, a stream of air is driven through the tube B, 

 and allowed to escape by the orifice in the upper side ; in so doing 

 it passes the front of the small capillary-tube A, and first having 

 sucked out the air, afterwards divides the stream of ether, which 

 has been driven by atmospheric pressure from the bottle J, into 



