CH. I'll.} 



COLL OP ION SECTLONING. 



159 



the chloroform is poured off and the carbol-xylene* clarifier (§ 302) 

 added. In a few hours the imbedded mass will become as transparent as 

 glass and the tissue will seem to have nothing around it. Sometimes 

 the collodion remains white and opaque for a considerable time. So far 

 as the writer has been able to judge, this is due to moisture. If one 

 breathes on the mass too much while imbedding, or if it is very damp 

 in the room, the opacity may result. Sometimes, in objects of consid- 

 erable size, this may remain for a week. This is the exception, how- 

 ever, and if the mass seems sufficiently hard and tough, the cutting may 

 proceed even if the clarification is incomplete. t 



Fig 132. Prep<xratio7i Vials for Histology and Embryology. These represent 

 the tzvo vials, natural size, that have been found most useful. They are kept in 

 blocks with holes of the proper size. 



In case the imbedding mass will not clarify after a few days the im- 

 bedded object may be placed in 95% alcohol for a day for dehydration, 

 and then passed through chloroform and into the clarifier. There is 

 usually no trouble in getting the mass perfectly clear in this way. 



* The hydrocarbon xylene (C 8 H 1() ) is called xylol in German. In English, mem- 

 bers of the hydrocarbon series have the termination "eue," while members of the 

 alcohol series terminate in "ol." 



fThe imbedded object may remain in the castor xylene clarifier indefinitely 

 without harm. The collodion grows somewhat tougher by a prolonged stay in it. 

 After cutting all the sections desired at one time, the imbedded tissue is returned 

 to the clarifier for future sections. 



