. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. Dental apparatus of Chilodon ornatus. (After Ehrenberg.) are composed of a hard substance; for when the soft parts of the animalcule are crushed between two plates of glass, they still remain distinctly visible, proving that they are of a denser texture than the rest of the body. Their number varies in different genera from sixteen to thirty, the former being the minimum and the latter the maximum yet observed. In animalcules thus provided with a dental appa- ratus the pharynx seems to have little to do with the act of n
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. Dental apparatus of Chilodon ornatus. (After Ehrenberg.) are composed of a hard substance; for when the soft parts of the animalcule are crushed between two plates of glass, they still remain distinctly visible, proving that they are of a denser texture than the rest of the body. Their number varies in different genera from sixteen to thirty, the former being the minimum and the latter the maximum yet observed. In animalcules thus provided with a dental appa- ratus the pharynx seems to have little to do with the act of nutrition ; indeed it frequently happens that while the little creature vibrates its cilia to produce the currents that bring it food, its mouth is kept open and motionless, so that the materials that serve for its nourish- ment pass through it unobstructed : but when first seized and bruised by the dental apparatus. In this case the buccal cylinder first of all expands in front to receive the morsel; it is then narrow posteriorly: but as the aliment passes onward it becomes contracted in front and dilates behind, so as to push the food towards the mouth. Sometimes, however, these movements can be witnessed without any large morsels of food being present in the dental cylinder. While the mouth is kept open, Monads and other animalcules may frequently be seen to enter it with facility as far as the intestine ; in which case the contraction of the denial circlet seems to serve to prevent its re- turn back again, should it try to escape in this direction. A very remarkable circumstance observable in these teeth is the rapid manner in which new sets are formed as often as the fissiparous habits of the animalcules render their repro- duction necessary. This regeneration of whole sets of teeth, a phenomenon so unusual among other races of animals, is among these Infu- soria a matter of every day occurrence, a new set being produced whenever spontaneous di- vision occurs: nay, should
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