CHAPTER VIII 

 IMBEDDING METHODS— INTRODUCTION 



155. Imbedding Methods. The processes known as Imbedding 

 Methods are employed for a twofold end. Firstly, they enable us 

 to surround an object, too small or too delicate to be firmly held 

 by the fingers or by any instrument, with some plastic substance 

 that will support it on all sides with firmness but without injurious 

 pressure, so that by cutting sections through the composite body 

 thus formed the included object may be cut into sufficiently thin 

 slices without distortion. Secondly, they enable us to fill 

 out with the imbedding mass the natural cavities of the object, 

 so that their lining membranes or other structures contained in 

 them may be duly cut in situ ; and, further, they enable us not 

 only to surround with the supporting mass each individual organ 

 or part of any organ that may be present in the interior of the 

 object, but also to fill with it each separate cell or other anatomical 

 element, thus giving to the tissues a consistency they could not 

 otherwise possess, and ensuring that in the thin slices cut from the 

 mass all the minutest details of structure will precisely retain their 

 natural position. 



These ends are usually attained in one of two ways. Either 

 the object to be imbedded is saturated by soaking with some 

 material that is liquid while warm and solid when cold, which is 

 the principle of the processes here called Fusion Imbedding 

 Methods ; or the object is saturated with some substance which 

 whilst in solution is sufficiently fluid to penetrate the object to 

 be imbedded, whilst, after the evaporation or removal by other 

 means of its solvent, it acquires and imparts to the imbedded 

 object sufficient firmness for the purpose of cutting. The methods 

 founded on this principle are here called Evaporation Imbedding 

 Methods. 



In any of these processes the material used for imbedding is 

 technically termed an " imbedding mass." 



There are two chief methods of imbedding — the paraffin 

 method and the celloidin or collodion method. 



The paraffin method is the one in most use ; for it is the more 

 rapid, requiring only hours where the celloidin process requires 

 days or weeks ; and it is the one which the most readily affords 

 very thin sections. But this only applies to fairly small objects ; 

 with objects of much over half an inch in diameter you cannot 



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