EARLY MICROSCOPICAL r>ISCOVERlES. Xlll 



" Malpighi,* in whose works may be detected the 

 germs of many important anatomical truths that have 

 subsequently been matured and established, says the 

 teeth consist of two parts, of which the internal bony 

 layers (dentine) seem to be composed of fibrous and, as 

 it were, tendinous capillaments reticularly interwoven. 



"Leeuwenhoek,f haying applied his microscopical 

 observations to the structure of the teeth, discovered 

 that the apparent fibers were really tubes, and he com- 

 municated a brief but succinct account of his discovery 

 to the Eoyal Society of London, which was published, 

 together with a figure of the tubes, in No. 140 of their 

 Transactions. This figure of the dentinal tubes, with 

 additional observations, again appeared in the Latin 

 edition of Leeuwenhoek's works, published at Leyden 

 in 1730. The dentine of the human teeth, and also 

 that of young hogs, is described as being ' formed of 

 tubuli spreading from the cavity in the center to the 

 circumference.' He computed that he saw a hundred 

 and twenty of the tubuli within the forty-fifth part of 

 an inch. He was aware also of the peculiar substance 

 now termed the cement, or crusta petrosa, which enters 

 into the composition of the teeth of the horse and the 

 ox. 



"These discoveries may be said to have appeared 

 before their time. The contemporaries of Leeuwen- 



* An Italian physician ; born in 1628 ; died in 1694. He was 

 the first to apply the newly-invented microscope in the study of 

 anatomy. 



\ A Dutch naturalist and manufacturer of optical instruments. 

 His microscopes were said to be the best in Europe. Besides 

 his dental discoveries, he discovered the red globules of the 

 blood, the infusorial animalcules, and that of the spermatozoa. 

 Bora in Delft October 24, 1632 ; died there August 26, 1723. 



