420 PROCEEDINGS OF SOCIETIES. 



In the discussion that followed, 



Mr. Needhara thought the pith would not give sufficient support 

 on all sides of the tissue. 



Mr. Groves approved of the combined use of pith and wax in the 

 way that had been shown, as overcoming many difficulties in the use 

 of wax for imbedding in a microtome, and as rendering the pith more 

 efficient in some cases. He did not prefer a microtome that had to 

 be held in the hand. 



Mr. Giles thought the small size of the bore of the instrument 

 might be at times objectionable. Suggested the use of dried carrot, 

 if pith could not be obtained ; it would swell and soften on the 

 addition of water, like pith. 



The Chairman objected to the pith-packing in the case of diseased 

 spinal cord, though in a healthy specimen the pressure exerted 

 might not be deleterious. On the whole, he thought the method 

 described simple, quick, and one giving comparatively no trouble ; 

 while the microtome, being held in the hand, was for some reasons 

 an advantage. He should certainly adopt the pith-process in 

 future. 



Mr. Golding Bird, in reply, stated that, if properly arranged, 

 equal support could be given to the specimen on all sides by the 

 pith, or even the combined use of wax with pith would overcome 

 every difficulty on that point. He thought that carrot on swelling 

 would be too hard to cut conveniently, or would exert too much 

 pressure. The only reason for using a microtome with small bore 

 was to save pith, and large specimens he did not as a rule imbed, 

 but cut by hand. Had never used pith with diseased and there- 

 fore softened spinal cords, but for normal nerve-tissue had seen it 

 used with the very best results ; a proper degree of hardening in some 

 fluid first was all that was required. 



Friday, July 17th, 1874. 



Shin Grafting. — Mr. Golding Bird read a paper on the mode of 

 growth of the new epithelium after skin grafting, or at the edge of 

 a skinning ulcer. Specimens illustrative of the subject were ex- 

 hibited. 



A summary of the changes observed is as follows : — A prolonga- 

 tion of the epithelium forming the rete raucosum of the adjoining 

 skin, in a horizontal direction over the surface of the neighbouring 

 granulation tissue ; the vertically placed cells of the rete mucosum 

 losing their upright position, and becoming more and more inclined 

 till quite horizontal ; the epithelial scales placed more superficially 

 taking no part in the process, but becoming shed, so that the new 

 epidermis was only one third the thickness of that of the skin from 

 which it had sprung. He ascribed the adhesion of the new epi- 

 dermis to the underlying granulation-tissue to the insertion of the 

 former into the most superficial layer of the latter, the inter- 

 cellular material of which may be seen becoming fibrillated like the 



