DEPARTMENT OF EXECUTIVE EMPATHY |
| DIRECTOR Turps Turpitude |
ABOUT
At a meeting of the Zoological Society of London (1832), Mr. Owen, on the occasion of exhibiting a large old cranium of the Capybara belonging to Mr. De la Fons, remarked, that perhaps the most extraordinary instance of the enlarged views which result from unwearied observation of the internal structure of animals is afforded by Cuvier's bold enunciation of the affinity of the Elephant to that order of the Mammalia which contains the most minute forms of the class, and, in support of that affinity, adduced the alveola; of the last molar tooth in Mr. Dc la Fons'a specimen as illustrating an additional analogy between the molars of the Rodent and those of the Elephant, namely, that the number of transverse lamina; increases as the jaw enlarges with age, the whole number not coming into use at once.
' In the Capybara' says Mr. Owen, 'the posterior grinders, like tho^e of the Elephant, present a greater number of component lamina than the anterior ones, which are of earlier formation. Those of the upper jaw, according to the figure and description in the " O^cinens Fossiles" (V. pi. 1, p. 24), are composed of eleven lamina', of which all but the first, which is notched externally, are simple. In the figure too, it is worthy of observation that the last or eleventh lamina is imperfect, and exhibits a construction analogous to the imperfectly-formed lamina; or denticles in the Elephant's grinder, viz. a division into component columns. In the work of M. F. Cuvier, " Sur les Dents des Mam mi feres," the number of laminee in the last grinder of the upper jaw of the Capybara is stated as "onzc ou duuze;" but eleven only are exhibited in the figure, and we may suppose therefore the doubt as to the precise number to be founded on uncertainty as to the propriety of considering the first deeply-notched lamina as single or double. In the cranium in the College Museum the number of the lamina} is twelve, the forked one being regarded as single. In Mr. De la Fons's specimen the alcenlce clearly indicate that the number of laminee of the last molar had been thirteen, with the rudiment of the fourteenth; the extent of the grinding surface is however proportionally longer than
would result from the additional laminee alone; for as these laminee do not cease to grow so long as the animal lives, they increase in thickness as age advances.' (Znnl. Prnc.)
Mr. Morgan (1830, Linn. Trans, vol. xvi.) describes Ihe stomach as formed by a single membranous bag; and, as in other mammiferous vegetable feeders in which this simple form of stomach is found, the coecum as large and complicated in proportion. Finding nothing requiring particular notice in the rest of the alimentary ranal, Mr. Morgan proceeded to examine the structure of the moulh and throat. After noticing the considerable extent of the grinding surfaces of the molar-teeth, he remarks that it must be obvious how necessary such an arrangement of parts must be to the health of the animal, when the nature of its food and the simple structure and limited functions of its most important digestive organ are considered, a provision being thus made for the proper mastication of the hard vegetable substances upon which the animal must occasionally subsist. But Mr. Morgan found another structure, undescribed up to the time when he made his examination, by which the process of perfect mastication is rendered indispensable to the passage of the food from the mouth to the stomach. This structure, by which the possibility of swallowing any portion of unmasticated nutriment is prevented, is shown in an extraordinary formation of the velum palati mollis, or soft palate. In other animals this membrane generally forms an imperfect floating septum, suspt-ndcd from the back part of the roof of the palate, and interposed between the cavity of the mouth and pharynx, but it was found in the capybara and in some of ils congeners to be much more extensive in its attachments, and different in its form and uses. On separating the jaws the mouth appears to terminate in a nearly blind pouch; for the communication with the pharynx seems as if shut by a strong membrane of a funnel shape, the concavity of which recedes towards the throat, ' This membrane is an extended velum palati attached to the whole circumference of Ihe fauces and root of the tongue, and is prevented from forming a complete septum by the existence of a small central circular aperture, by which a communication between the mouth and the pharynx is established for passage of food: so that through this small membranous funnel, or strainer (if I may be allowed the expression), it is physically impossible that any considerable portion of unmasticated nutriment should find its way, by natural means, from the mouth into the alimentary canal: and from this circumstance the first process towards digestion must be rendered certain and complete; for the grosser particles of food must remain in the mouth from the interposition of the membranous sieve or strainer, which is thus placed between the organs of mastication and those of digestion.' Mr. Morgan observes that the same provision for the complete mastication of all solid substances, previous to their being swallowed, will be found in others of the same group, but he confines his well executed descriptions and figures of the anatomy of these parts to the dissections ho had made of the capybara. To these descriptions and figures we refer ihe reader, offering only the conclusion to winch Mr. Morgan comes as to the use of this conformation of the velum palati: this appears to him to have reference to the digestive organs, and to.be confined almost entirely to the process of deglutition.