166 COLLODION AND OTHER IMBEDDING METHODS. 



object is soaked in oil of origanum (Oleum Origani vulg.). It 

 is then brought into a mixture of origanum oil and paraffin, 

 heated to not more than 40 C., and lastly into a bath of 

 pure paraffin. 



The mass may be preserved in the dry state, and may be 

 cut dry. 



RYDER (Queen's Micr. Bull., 1887, p. 43; Journ. Roy. Mic. 

 Soc., 1888, p. 512) has modified the process by substituting 

 chloroform for the origanum oil. He states that sections 

 chain more easily than even in ordinary paraffin imbedding. 

 They may be cleared for mounting either with chloroform or 

 with Weigert's xylol and carbolic acid mixture (supra, 298. 

 Ryder says, " equal parts," but Weigert's formula is as 

 above given). 



Other Evaporation Masses. 



300. Joliet's Gum and Glycerin Method (Arch. Zool. exp. et 

 gen., x, 1882, p. xliii; Journ. Roy. Mic. Soc. (N.S.) ii,^1882, p. 

 890) . Pure gum arabic dissolved in water to the consistency 

 of a thick syrup. (Solutions of gum sold under the name of 

 strong white liquid glue (" colle forte blanche liquide afroid") 

 may also be used ; they have the advantage of having a uni- 

 form consistency.)* Pour a little of the solution into a watch- 

 glass, so as not quite to fill it, add from 6 to 10 drops of pure 

 glycerin, stir until thoroughly mixed. 



Between the limits of 6 to 10 drops of glycerin the propor- 

 tions most suitable to the nature of the object and to the 

 season of the year must be found by experimental trials. In 

 the winter or in rainy weather less glycerin should be taken 

 than in the summer or dry weather. 



It is often well to soak the object in glycerin before putting 

 it into the mass. In this case less glycerin should be added 

 to the gum, in proportion to the amount of glycerin contained 

 in the object. 



The object is imbedded in the mass in the watch-glass, and 

 the whole left to dry for from one to four days. When it has 

 assumed a cartilaginous consistency, a block containing the 

 object is cut out, turned over, and allowed to dry again until 



* It is highly probable that these commercial preparations contain gelatin, 

 and perhaps some other gum besides gum arabic. 



