149 



XXVII. — On a New Medium for Mounting Fresh or Moist Animal 

 and Vegetable Structures. By H. Deane, Esq. 



(Read March 19, 1851). 



As the subject of this paper is one of general interest and utility 

 to every microscopist, and sufficient time has been taken to test its 

 success, I trust I shall need no apology for presenting it to the notice 

 of the Society. 



The material to be described is intended to remedy some of the 

 inconveniences of mounting objects in fluid, which are most felt by 

 those who only use that method occasionally, as well as certain de- 

 fects attending the use of Canada balsam. 



The inconveniences alluded to are : — 



1st. The necessity of employing, in most cases, some kind of cell 

 to contain the fluid and objects, the cementing or constructing of 

 which causes extra work, and oftentimes prevents the object from 

 being seen under high powers, as the ^th or T Vth of an inch. 



2nd. The objects not being permanently fixed, and, if consisting 

 of numerous small particles, the slides requiring to be kept in a 

 horizontal position. 



3rd. The difficulty of obtaining any fluid capable of preserving 

 vegetable and animal preparations in their natural colours, and in 

 other respects without alteration. 



4th. The danger of losing a valuable specimen by the evaporation 

 of the fluid caused by the cracking of the cement, arising from any 

 casual violence. 



5th. The obliterating effect of Canada balsam on some structures. 



It has long been a desideratum to obtain a perfectly transparent 

 substance for mounting objects containing their natural juices, which 

 possesses the same facilities in use as Canada balsam, for the least 

 moisture in the object causes the latter to appear milky and full of 

 bubbles. Various attempts have been made, from time to time, to 

 mount objects in solutions of gum Arabic, isinglass, gelatine, &c, 



