BV T. STEEL. 325 



precipitated from the saliva. He mentious its occurrence in the ox and sheep, 

 and remarks that on account of its yellow colour it is freqiiently mistaken for 

 gold. He quotes the analysis by Berzelius mentioned above. 



In a paper published in 1879, "On Macrodontism." N. de Miklouho-Madayt 

 described and figured the huge projecting teeth which he observed in natives of 

 the Taui or Admiralty Islands, and refers to a sketch in Xature* which he de- 

 scribes, liowever, as a caricature. In a subsequent paperf he explains that fur- 

 ther investigation had shown that he was mistakin in supposing that the projec- 

 tions were due to dental malformation, but that they really consisted of an enor- 

 mous deposit of '"tartar," probably largely due to the habit of these people of 

 chewing betel nut and lime. The deposit could be detached, leaving the teeth 

 quite normal. The late Mr. P. R. Pedley, surgeon-dentist, who examined the 

 deposit, identified it as dental tartar. Unfortunately there is no record of a 

 chemical examination having been made. Miklouho-Maelay proposed the term 

 "odontolithiasis" fur this condition. 



From the stocks of bones passing through a large bone charcoal factory in 

 Sydney, I have been able to examine the teeth o*' numerous sheep and also those 

 of oxen, horses, pigs, etc., and to secure ample material for a complete chemical 

 analysis of the deposit from the teeth of sheep and oxen . From other sources 

 I have obtained sufficient for (]uantitative analysis from the teeth of a number 

 of animals, including man. By the courtesy of the late Mr. R. Etheridge, speci- 

 mens from the teeth of animals in the Australian Museum, Sydney, were secured, 

 sufficient in a few cases for full analysis, and in a considerable number of others 

 for qualitative determination. Mr. H. A. Longman, F.L.S., Director of the 

 Queensland Museum, kindly allowed me material from the skeleton of a camel. 

 In all such cases care was taken to insure that the dejiosit obtained was pure and 

 not contaminated with lime whicii may have been used in the preparation of 

 skeletons . 



Very eommonlv the taxidermists api)ear to have carefully cleaned the teetii. 

 My kinsman. Mr. A. Ross Brown, B.D.Sc, L.D.S.. of Windsor, Melbourne, and 

 nw friend, Mr. J. Dartou, surgeon dentist. Petersham, furnished me with an ample 

 supply from human teeth, secured in the course of their professional practice in 

 the operation of "scaling." Mr. Charles Hedley, Acting Curator of the Aus- 

 tralian Museum, kindly gave me facilities, with the aid of Messrs. Thorpe and 

 Troughton, to examine the large collection of skulls in the Museum. To Pro- 

 fessor J. Douglas Stewart, of the Veterinary School, Sydney University, I am in- 

 debted for explaining to me details regarding the structure of teeth and giving 

 me other information. To all of these gentlemen I desire to tender my best thanks. 

 Further material was obtained from specimens in my own collection and passing 

 through my hands. In addition 'to examining the dental deposit, I have, in the 

 cases of the ox and camel, made an analysis of the cement or cementum layer 

 (cntsta petrosa). In these animals this layer is strongly developed, extending 

 well up on the exposed part of the tooth, and can be readily separated. The 

 incrustation could, in most cases, be easily flaked off from either the cement or 

 the enamel and the surface beneath was always f|uite sound. 



The figures following give the results. The samples were ground, and air- 

 dried at ordinary temperature. 



tProc. Linn. Soc. N.S. Wales, iii., 1879, p. 169. 



•Nature, xvi., 1877, p.a.'jl. 



tProe. Linn. Soc. N.S. Wales, x., 1886. p.682. 



