VAMOUS INFILTRATION METHODS. 141 



CHAPTER XV. 



IMBEDDING METHODS, PARAFFIN AND OTHER FUSION MASSES. 



267. As to the Various Infiltration Methods. Amongst the 

 very various methods of infiltration-imbedding that have been 

 proposed, two are pre-eminently important the paraffin 

 method, for small objects, and the celloidin or collodion 

 method for large objects. 



The subject of the respective merits of paraffin and celloidin 

 still affords matter for discussion to some persons. The case, 

 however, seems to be a very simple one. Celloidin does not 

 afford by a long way the thinnest sections that are obtainable 

 with small objects. For such objects it is therefore not equal 

 to the demands made by modern minute anatomy, and paraffin 

 must be taken. On the other hand, paraffin (as at present 

 employed), will only cut very thin sections with small objects 

 with objects of 7 millimetres diameter you cannot get with 

 paraffin thinner sections than you can with celloidin ; and if 

 you try to cut in paraffin objects of /somewhat greater size, 

 10 mm. and upwards, it will probably happen that you will not 

 get perfect sections at all, blocks of paraffin of this size having 

 a tendency to split under the impact of the knife. So that 

 for large objects, celloidin gives better results. 



I have not been able to satisfy myself that the preservation 

 of the tissues is better in celloidin sections than in paraffin 

 sections ; so that convenience apart the case remains as 

 above stated, paraffin for small sections, celloidin for large 

 ones. 



To this must be added aqueous masses, such as gum or 

 gelatin, for very special cases. 



It is the purpose of this chapter to describe the paraffin 

 method, and to mention some other masses that can be em- 

 ployed in a similar manner. 



