204 SOME REMARKS ON CLARIFICATION, ETC. 



tions ; some non-metallic substance, such as a quill tooth-pick, 

 should be used instead. 



Having stained the specimen, the next step is to wash it, dehy- 

 drate, and clear it. Clearing means removing all those substances 

 which are of a lower specific gravity than the medium the speci- 

 men is to be mounted in. The clearing agents are : oil of cloves, 

 oil of cedar, oil of bergamot, and oil of sandal wood. Oil of 

 cloves is by far the most commonly used. 



Some IRemarfea on Clarification, anb aleo 

 on a IRew Clarifier for flDicro6cop(cal 



purpoeee/' 



By Edwin A. Schultze. 



(Read October igth, i8g4.) 



ONE of the most important points to be observed in micro- 

 scopical research is the requisite clarification of the object 

 under examination. As simple, however, as this appears, the 

 views of the different authorities who have investigated the subject 

 do not appear to coincide. In studying plant sections, clarification, 

 according to Dippel, is resorted to to produce the necessary 

 transparency of the object, which on account of its contents does 

 not permit of a thorough investigation of the inner structure. The 

 usual clarifiers mentioned by Dippel are: Liquor potassse (in some 

 cases to be used with acetic acid and ammonia) ; potassic alcohol, 

 carbolic acid (when necessary to be used after treatment with 

 alcohol or mixed with turpentine); and finally chloral hydrate 

 (8 parts dissolved in 5 of water). Zimmermann, in his work 

 Botanische Mikrotechnik^ discriminates between the action of 

 the above named chemical clarifiers and the clarification by means 

 of more or less refractive mounting media, especially essential 

 oils, balsams, and resins. Of these latter he mentions Canada 

 balsam, dammar and Venetian turpentine. Tschirch, in his 

 " Pflanzen anatomic," speaks of employing only liquor potassse and 



* Translation from the German of Dr. Wilhelm Lenz, Zeitschr. f. wiss. 

 Mikr. xi. 16 (1894), for the Journal of the New York Microscopical Society. 



