COLLODION AND OTHEE IMBEDDING METHODS. 137 



then decalcify cautiously the exposed half of the specimen, 

 wash, and stain it. In this way von Koch was able to 

 demonstrate the most delicate lamellae of connective tissue 

 in Isis elongata. 



This method was imagined in order to enable the hard and 

 soft parts of corals to be studied in their natural relations. 

 It is evidently applicable to the study of any structures in 

 which hard and soft parts are intimately combined. For 

 purposes such as these it is certainly a method of the greatest 

 value. 



173. EHRKNBAUM'S Colophonium and Wax Method (Zeit. f. 

 pits. J//fc., 1884, p. 414). Ehrenbaum recommends that the 

 objects be infiltrated with a mass consisting of ten parts of 

 colophonium to one of wax. The addition of wax makes the 

 mass less brittle. Sections are obtained by grinding in the 

 usual way. The mass is removed from them by means of 

 turpentine followed by chloroform. 



174. JOHNSTONE-LAVIS and VOSMAER'S Balsam Method (Journ. 

 Roy. Hie. Soc., 1887, p. 200) Alcohol material is carefully 

 and gradually saturated, first with benzol, and then with thin 

 and thick solution of benzol-balsam. It is then dried for a 

 day in the air and for several days more in a hot-air bath. 

 When hard it is ground in the usual way. For further 

 details and figure of the dry ing- stove see the original, which 

 claims for the method several advantages over that of von 

 Koch. 



175. WEIL'S Canada Balsam Method (Zeii.f. iciss. Mik , v, 2, 1888, 

 p. L'lH) ; Journ. Roy. Mic. Soc., 1888, p. 1042). 



176. GIESBEECHT'S Shellac Method. For hard parts only, spines of 

 Echinus, shell, etc., see Morph. Jahrb., vi, 1880, p. 95, or the abstract in 

 LEE und MAYEB, Grundziige, etc. 



Congelation Masses. 



177. The Freezing Method. Fresh tissues may be, and are, 

 frequently frozen without being included in any mass, and in 

 certain cases very satisfactory sections can be obtained in this 

 manner. But the formation of ice crystals frequently causes 



