THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL 



YOL. I. 



New Yoek, September, 1880. 



No. 9. 



Carbolic Acid in Balsam- 

 mounting. 



BY C. M. VOECE. 



On page 139 of Science Gossip, 

 for June 1880, a correspondent re- 

 marks on the use of carbolic acid 

 for mounting in balsam. This was 

 a new idea to me when I read it, 

 and I immediately tried the process 

 with most excellent results. The 

 first experiment was to place a drop 

 of the acid on a slide, into which I 

 dropped a very minute living fly ; 

 one of those that swarm around a 

 heap of vegetable refuse, especially 

 fruit ; placing the slip on the stage 

 of the microscope, the fly was seen 

 to struggle for but a few seconds, 

 when the limbs, wings and tongue 

 became extended, the whole insect 

 became beautifully clear, appearing 

 as if wholly destitute of viscera, 

 but exhibiting clearly the sexual 

 organs. Now removing the slip, 

 the acid was drained away, a drop 

 of moderately thick balsam was put 

 on, a cover applied and the com- 

 pleted mount examined. It had all 

 the appearance of an ordinary good 

 balsam-mount from turpentine or 

 oil of cloves, but less than five 

 minutes had elapsed since the living 

 fly was dropped into the acid. This 

 was in June, and the slide now 

 shows no change. 



Since that time I have used the 

 acid a great deal and esteem it an 

 invaluable aid in the examination 

 of insects, etc., and for mounting 

 small objects, Acari, Hemiptera, 



etc., in balsam, and very useful in con- 

 sequence of the speed with which 

 the result is obtained. I think, 

 however, its greatest value is in the 

 examination of specimens put into 

 it alive, for it seems to me even to 

 preserve the fluids of the insect, 

 though it renders them completely 

 colorless. If pressure be applied 

 to an insect thus treated with the 

 acid, the body-walls will be ruptur- 

 ed, and, if in balsam, a colorless, 

 glassy fluid will exude, sometimes 

 carrying distinct cells immersed in 

 it, and this extravasation will re- 

 main permanent in the mount. I 

 have tried to obviate this by making 

 an opening in the body-wall and 

 applying pressure to the object 

 while in the acid, then dissecting 

 away the extruded matter before 

 applying the balsam, but the mar- 

 gins of the opening will show an 

 unsightly, ragged edge in spite of 

 all efforts. 



Therefore, in all cases where I 

 have used it lately, I have mounted 

 without pressure, using for very 

 minute objects a sufiiciently deep 

 layer of balsam, and for thicker 

 objects, such as fleas, bed-bugs, etc., 

 rings of tin-foil, lead or gutta-percha, 

 of suflicient thickness to permit a 

 little pressure but to prevent crush- 

 ing. 



A very advantageous feature of 

 this process is that the acid does 

 not stiffen or harden the object, but 

 it remains perfectly flexible for a 

 long time, and the object may be 

 arranged so as to display its features 



