168 



THE AMEKICAN MONTHLY 



[September, 



consumed, in the one case by the lar- 

 vae of the fly and in the other (/. e., 

 when mixed with sugar), by the fly 

 itself, shows that this insect may de- 



vegetable tissues for section cutting, 

 while it has many advantages over 

 all other devices employed for the 

 same purpose. 



Microscopists who are interested 

 in the study of histology and patho- 

 logy, have long felt the necessity for 

 a better method of freezing animal 

 and vegetable tissue, than has been 

 heretofore at their command. 



In hardening tissues by chemical 

 agents, the tissues are more or less 

 distorted by the solutions used, and 

 the process is very slow. Ether and 

 rhigolene have been employed with 

 some degree of success, but both are 

 expensive, and they cannot be used 

 in the presence of artificial light, be- 

 cause of danger of explosion. An- 

 other disadvantage is that two per- 

 sons are required 

 to attend to the 



manipulations, 

 one to force the 

 vapor into the 



freezing box, 

 while the other 

 uses the section- 

 cutting knife. 



Fig. 37. 



stroy microscopic germs as well as 

 disseminate them, and indicates that 

 in some cases its agency in keeping 

 down their number may more than 

 counterbalance its action in contribut- 

 ing to their dissemination. 



Dr. Thomas Taylor, exhibited and 

 described his improved freezing mi- 

 crotome, and exhibited the instru- 

 ment in operation. It is figured in 

 the accompanying illustration, and 

 briefly described as follows : — 



Taylor's freezing microtome. 



This microtome presents all the 

 advantages of any plan heretofore 

 employed in hardening animal or 



The moment 

 the pumping of 

 the ether or rhigo- 

 lene ceases, the 

 tissue operated 

 on ceases to be 

 frozen, so ephe- 

 meral is the de- 

 gree of the cold 

 obtained by these 

 means. 



The principal 

 advantages to be 

 obtained by the use of this microtome 

 are, ist, great economy in the method 

 of freezing, and, 2d, celerity and 

 certainty of freezing. With an ex- 



