The celebrated anatomist ADRIAN SPIEGEL (1578 to 1625), better known by the Latinized name of _Spigelius_, wrote nothing noteworthy about the teeth, but he appears to have been the first to affirm that the teeth are more firmly fixed in the alveolus, when their roots are curved after the manner of hooks.[351] DIEMERBROEK, a Dutchman, relates several cases of dental anomalies, as for example, of teeth being cut in the palate, and which injured the tongue. The author cites his own case, relating that having had a canine tooth extracted when well advanced in years, it was, nevertheless, succeeded by a new one. He relates, besides, that he had seen in Utrecht a woman, aged fifty-six years, who again cut two incisors after having lost the former ones two years previously. Apart from this, Diemerbroeck tells us nothing of interest or importance regarding the teeth, often repeating old ideas, the falseness of which had already been luminously demonstrated. For instance, he says that the permanent teeth are developed from the roots of the deciduous ones remaining in the alveoli; an unpardonable error for an anatomist of the seventeenth century, for which he was afterward taken to task by Duverney.[352] THOMAS BARTHOLIN, whom we have already mentioned, speaks of a tooth which had made all the round of the alveolar border; that is to say, of a dental arch constituted by a single piece; and the Italian anatomist BERNARDO GENGA makes mention of an analogous case.[353] It is superfluous to add that these authors allowed themselves to be deceived by false appearances, owing especially to an abundant and uniform deposit of tartar on the surface of the teeth and in their interstices, which gave to the dental arch the appearance of one continuous piece. RINALDUS FREDERICUS, in his erudite dissertation entitled _De dentium statu naturali et præternaturali_, spoke of the dental system with sufficient thoroughness, if we consider the epoch in which he wrote. He commences his work with a long chapter on the importance and dignity of the teeth (_dignitas dentium_). Among other things, he relates that formerly, in certain parts of India, the teeth were so highly valued as to be offered in sacrifice to the gods. He says, too, on the authority of certain authors, that the ancients were led to believe that the teeth served for the resurrection of the body, from the circumstance of their not showing signs of corruption when found in sarcophagi. Discoursing of the genesis of the teeth, Fredericus says that “every tooth is at first enclosed within a follicle, that is, in a frail, skin-like membrane, in the same manner as the grain in the wheat-ear.” Taking this comparison as his point of departure,[354] he gives to dentition the name _germination_.