METHOD OF LOCALIZED (EDEMA. 75 



carminateof ammonia, whilst the elastic fibres are colored 

 yellow. 



Preparation 5. In most of the larger animals 

 (e.g. the dog), the connective tissue is, in the adult, 

 so densely pervaded by the bundles of while fibres 

 as to render it impossible to obtain a film delicate 

 enough for easy observation without tearing the 

 texture with needles, and thereby distorting the 

 cellular elements. Or, on the other hand, it may be 

 desired, even in those animals in which such delicate 

 tissue as that the preparation of which has just been 

 described is found, to obtain a specimen from a part 

 where the connective tissue is not naturally extended 

 in so advantageous a manner for preparation and 

 observation. In these cases the following method 

 may be employed with advantage : 



In a recently killed dog a flap of skin is dissected 

 back, and a Pravaz or 'other hypodermic syringe 

 (Fig. 17), provided with a fine canula, having been 



Fig. 17. 



Pravaz syringe for interstitial injections; c, the cauula. The syringe is 

 glass with ebonite fittings ; the canula is a fine perforated steel 

 needle set in ebonite. Natural size. 



previously filled with salt solution, the point of the 

 canula is inserted underneath the layer of connec- 

 tive tissue which is most superficial on the reflected 

 portion of skin, and a little of the fluid is forced out. 

 This does not immediately diffuse itself uniformly 

 through the loose areolar tissue, but remains for a 

 short while at the same place, forming a little bulla 

 of liquid bounded and covered in by a film of tissue, 



