1888.] MICKOSCOPICAL JOURNAL. 49 



completed. Pour oft' the stain, and cover the sections with rectified spirit. 

 The spirit must not be filtered, but must be poured on to the sections, and 

 the watch-glass must then be taken in the hand and turned rapidly round 

 and round for about a minute. After this the spirit is poured oft' quickly, 

 and the sections are now covered with an alcoholic solution of picrate of am- 

 monia, which is prepai"ed as follows : — 



Make a saturated solution of picric acid in absolute alcohol ; to 40 cc. of 

 this solution add 50 cc. of strong ammonia, and slowly evaporate the mix- 

 ture down to dryness. Make a saturated solution of the resulting crj^stals in 

 absolute alcohol. 



The sections are left in this solution for five miniites ; they are then rinsed 

 quickly in absolute alcohol or rectified spirit, cleared in oil of cloves, and 

 mounted in Canada balsam. If a section is now examined under the micro- 

 scope, it will be seen that it is stained most beautifully and selectively^the 

 picric acid producing a golden yellow, and the carmine a pink or pale red 

 color, very soft and pleasing to the eye. 



For some years I have employed a modification of the above process for 

 staining vegetable tissues in carmine and green, the old processes being both 

 tedious and not always 3'ielding satisfactory results. 



The sections are treated as described, down to the washing after staining 

 with the carmine ; they are then transferred to a glass beaker, containing 90% 

 alcohol at 100° Fahr., and are kept at this temperature over a water bath for 

 half an hour ; or if time is no object, the sections should be washed for 

 several hours in successive changes of cold alcohol. This ti"eatment almost 

 totally removes the yellow stain. The sections are then stained for one hour 

 Vtdth a strong alcoholic solution of iodine green, washed in rectified spirit, 

 cleared in oil of cloves, and mounted in Canada balsam. Two precautions 

 must be observed : — (i) the sections must not be kept in the spirit used for 

 washing more than two or three minutes ; and (2) they must be mounted 

 within one hour after being transferred to the clove oil. 



It may happen that the iodine green employed tends to combine with the 

 carmine, the beautiful color of which is thereby completely spoiled. This 

 action of the green may be partially corrected by washing the sections in al- 

 cohol acidulated with a few drops of acetic acid ; but it is much better to try 

 different samples of iodine green, until one is found which leaves the carmine 

 perfectly clean. 



A very beautiful carmine and blue stain is obtained by substituting anilin 

 or pure opal blue, in an alcoholic solution, in place of the iodine green in the 

 above process. 



In sections of the stems and petioles of many palms and other monocotyle- 

 dons, certain cells in the fibrovascular bundles (possibly the spiral on pitted 

 cells — I have not examined a longitudinal section) persistently retain the 

 yellow produced by the picric acid, and a perfect triple stain is thus obtained, 

 which is seen most clearly under a quarter-inch objective. 



The following combinations yield ver}' beautiful results in many vegetable 

 sections : — 



1. Eosin and iodine green. 



2. Rosein and pure opal blue. 



3. Bismarck brow^n and pure opal blue. 



4. Bismarck brown and violet. 



5. Iodine green and Bismarck brown. 



6. Eosin and methyl-blue. 



PICRO-CARMINE FOR ANIMAL TISSUES. 



Dissolve I gramme of carmine in 50 cc. ammonia, and add 200 cc. of a 

 cold saturated solution of picric acid. Evaporate the mixture down to 100 



