94 CHAPTER VII. 



spirit lamp, and with it a hole is melted in the end of the 

 cylinder; the specimen is pushed into the melted paraffin, 

 and placed in any desired position. The advantages of the 

 method lie in the quickness and certainty with which it can 

 be performed. 



There remains the watch glass method. Melt paraffin in a 

 watch glass, and throw the object, previously well de- 

 alcoholised and penetrated with a solvent, into it; or place 

 the object in the watch glass, add solid paraffin, and heat. 

 After the mass has hardened, cut out a block containing the 

 object (this is of course applicable to other masses, such as 

 celloidin). This should be done with a thin-bladed knife, 

 slightly warmed. If paraffin be used you may, instead of 

 cutting out a block, turn out the whole mass of paraffin by 

 simply warming rapidly the bottom of the glass, but I find 

 it is far safer to cut out a block. To facilitate the removal 

 of the mass some persons lubricate the watch glass before 

 pouring in the mass. To do this a drop of glycerin or, 

 according to some, clove oil, should be smeared over it and 

 wiped off with a cloth until hardly a trace of it remains. 

 But this is not necessary. 



As regards small objects at all events, I consider the 

 watch glass process to be the very best of any. 



For imbedding very small objects in this way certain precautions may be 

 necessary in order not to lose them. SAMTEE (Zeit.f. iviss. Mik., xi, 1894, 

 p. 469) saturates small unstained objects with paraffin that has previously 

 been strongly coloured with alkanna extract, and then imbeds them in pure 

 paraffin. The objects do not stain with the alkanna. B.HUMBLER (ibid., 

 xii, 1895, p. 312 ; and xiii, 3, 1896, p. 303) stains previously the objects 

 themselves lightly with eosin dissolved in strong alcohol, and removes the 

 stain from the sections with weak alcohol. See also ibid., xiii, 2, p. 200, a 

 paper by SCHYDLOWSKI ; and in Zeit. f. wiss. Zool., Iviii, 1897, p. 144, a 

 process of BORGERT. 



127. Choice of a Method. Amongst the very various 

 methods of imbedding that have been proposed two are pre- 

 eminently important the paraffin method for small objects, 

 :nnl the celloidin or collodion method for large objects; 

 indeed these are the only ones that have survived in general 

 use. 



The subject of the respective merits of paraffin and cel- 

 olidin still affords matter for discussion. The case, however, 



