CHAPTER XXIX. 373 



Soc., 1885, p. 348) says that perfectly fresh portions of bone or teeth 

 may be ground with emery on a dentist's lathe, and good sections, with 

 the soft parts in situ, obtained in half an hour. 



HOPEWELL- SMITH (Journ. Brit. Dent. Ass., xi, 1890, p. 310; Journ. 

 Roy. Mic. Soc., 1890, p. 529) says that for preparing sections of teeth 

 showing odontoblasts in situ the bast plan is to take embryonic tissues. A 

 lower jaw of an embryonic kitten or pup may be taken, and hardened in 

 solution of Miiller followed by alcohol, then cut with a freezing microtome. 



WEIL (loc. cit., 180) fixes pieces of fresh teeth in sublimate, stains 

 with borax -carmine, brings them through alcohol into chloroform and 

 chloroform -balsam, and after hardening this by heat proceeds to grind 

 as usual ( 177). 



See also EOSE, 773. 



775A. For the study of the vessels in teeth, LEPKOWSKY (Anat. 

 Hefte, viii, 1897, p. 568) injects with Berlin blue, hardens the teeth 

 with a piece of the jaw for one or two days in 50 per cent, formol, 

 decalcifies in 10 per cent, nitric acid (eight to fourteen days, change 

 frequently) and makes celloidin sections. 



For decalcification of teeth, see also 546 (ROUSSEAU, BODECKER 

 and FLEISCHMANN). Bodecker finds Rousseau's process not appli- 

 cable to human teeth : the acid must be added to the fluid celloidin. 



For the study of the lymphatics in the dental pulp, DEWEY and 

 No YES (Dental Cosmos, lix, 1917, pp. 436 44) first inject the 

 blood vessels with carmin-gelatin. Then 2 grms. of Prussian blue 

 (oil colour in tubes) is stirred with 3 grms. of turpentine oil in a 

 glass mortar for five minutes ; 15 grms. of sulphuric ether is added, 

 and this fluid filtered through flannel or chamois skin. After the 

 injection of this fluid the head is placed for twenty-four hours or 

 longer in 20 per cent, formalin, and then the injected teeth are 

 carefully removed and the pulps examined. Later it was found 

 that more constant results were obtained when the injection of the 

 blood vessels followed that of the Prussian blue. Prussian blue 

 injected directly into the pulps and trypan blue or lithium 

 carmine injected intravenously or intraperitoneally were also 

 employed. See 780 and 790. 



WELLINGS (Proc. Sixth Internat. Dent. Cong., pp. 47 et seq.) demon- 

 strated intra-vitam staining of dental and adjacent tissues by means 

 of trypan blue ( 780). 



MUMMERY (Phil. Trans. B., ccii, 1912), for the fixation of the 

 nerve-tissue of the dental pulp, finds formalin to be preferable to all 

 other fixing agents, employing 10 parts of the 40 per cent, com- 

 mercial formalin to 90 parts of water. 



Decalcification is effected by means of 33-3 per cent, formic acid. 

 After thorough washing he leaves for twenty-four hours in a strong 



