But even while putting in doubt the existence of dental worms, he believes it his duty to enumerate the various remedies, recommended for their destruction. As to fumigations with the seeds of the hyoscyamus, Houllier, declares that what is believed by the common people, and what has been written by doctors of antiquity about worms being killed and seen to fall from the teeth by the effect of these fumigations, is all nonsense. In fact, he says, when the seeds of the hyoscyamus are burnt there fly away from them what appear to be little worms, even if the fumes do not reach the worm-eaten tooth. (_Quod autem vulgus sibi persuadet, et ab antiquis medicis scriptum est de suffumigio è semine hyoscyami, videtur fabulosum. Nam inde ajunt manifeste vermes excidere. Re vera, incenso semine, evolant tanqua vermiculi, etiam si non attingit fumus vermiculosum dentem._) Apart from this, in the works of Houllier, nothing is found that is of interest for the history of dentistry. He repeats several errors and prejudices of the ancients; he says, for example, that men have ordinarily thirty-two teeth, women, twenty-eight; and he, too, believes in the expulsive virtues of the fat of green frogs when applied to a tooth (_adeps ranæ viridis dentem depellit_). Houllier does not contribute in any way to dental therapeutics, he only enumerates the methods of cure recommended by preceding authors.[310] VOLCHERUS COITER (1534 to 1600), of Gröningen, an ardent student of anatomy, and a pupil of Fallopius, Eustachius, and Aranzio, studied with great attention the development of bones, dissecting many fetuses and children of various ages for that purpose. He clearly states his opinion that the teeth are not bones, since they do not pass, like the latter, through the cartilaginous stage, but are derived instead from a mucous substance.[311] JOHANN JACOB WECKER, a doctor of Colmar, published in 1576 a valuable medical work composed of synoptical tables, in which is briefly summarized the best of what had been written by preceding Greek, Latin, and Arabic authors. One gathers from this author that at the time in which he wrote it was considered an excellent preservative against the plague to rub the teeth with theriac, mithridate, angelica, and zedoary. From this it may be perceived that even in those days doctors had understood the importance of the cleanliness and disinfection of the mouth as a prophylactic against infective diseases. In the above-mentioned book may be found a sufficiently complete exposition of dental therapeutics of that and of the preceding periods. There is nothing, however, which is not already known to us from our examination of the earlier writers. Worthy of notice is the information that, among other things, to facilitate the cutting of teeth rubbing the jaws with turpentine was recommended at that time.[312] [Illustration: Volcherus Coiter.]