MUCUS. 



481 



velocity being about 10 feet per second, its 

 maximum action will be | (420) = 185, and it 

 will move at the rate of ' 3 or 3|rd feet per se- 

 cond, being about 2f miles per hour. With 

 the help of these formula the maximum forces 

 of any other animals may be found. 



BIBLIOGRAPHY. ^Aristotle, On the progressive 

 motion of animals, by Taylor. Fabricitis ab Aqua- 

 pendents, De niotu locali anirnalium, Opera ed. 

 Bohnii, Lipsiae, 1687, p. 332. Gassendi, De vi. 

 motrice et motionibus animaliiim, Opera, torn. ii. 

 lib. xi. Florentine, Burelli, De motu animalium, 

 4to. Lugduni, 1685. Haller, Elementa physio- 

 logic, torn. iv. lib. xi. sect. iv. Burthen, Nouvelle 

 mecanique des mouvemens de 1'homme et des ani- 

 inaux, 4to. Par. 1798. Magendie, Precis element, 

 de physiol. tome i. Roulin, Recherches sur le 

 mecanisme des attitudes et des mouvemens de 

 rhomme, in Magendie's Journal, torn. i. ii. 1821-2. 

 Gerdy, Sur le mecanisme de la marche de 1'homme, 

 Magendie's Journ. torn, ix, and Physiol. medicale 

 diJactique et critique, par P. N. Gerdy, Paris, 1833, 

 tome i. partie 2. Kruuse, Handb. der menschl, 

 Anat. Bd. 1. Poisson, Traite de mecanique, Paris, 

 1833, tome ii. Weber, W. and E., Mechanik der 

 menschl. Gehewerkzenge, Gott. 1836. Kirby and 

 Spence, Introduction to entomology, 8vo. Midler, 

 Elements of Physiology by Baly. Roget, Bridge- 

 water Treatise. Paley, Natural theology, with notes 

 by Brougham and Bell Gregory, O., Treatise of 

 mechanics. Chabrier, Memoire de 1'Acad. torn. ii. 

 Sur le vol des Insectes, et observations sur 

 quelques parties de la mecanique des mouve- 

 mens progressifs de 1'homme et des animaux ver- 

 tebres, 4to. Paris, 1823. Straus Durckheim, Con- 

 siderations generales sur 1'anatomie comparee des 

 animaux articules, 4to. Paris, 1828. Cuvier, Regne 

 Animal. Perrault, Mecanique des animaux. Pa- 

 rent, On animal mechanics, A. P. 1702. Marian, 

 On the position of the legs in walking, A. P 1721. 

 Bortrgelat, On the motions of the Horse. Bernoii- 

 illius, J. De motu musculorum, Lond. 4to. 1708. 

 Emerson's Piinciples of mechanics, Lond. 4to. 

 1800. Pinel, On animal mechanics, Roz. xxxi. 350, 

 xxxiii. 12, xxxv. 457. Mayow, J. De motu mus- 

 culaii et spiritibus animalibus. 



(John Bishop.) 



MUCUS (from /*t/f, the secretion of the 

 Schneiderian membrane). This word has been 

 used in so very indefinite a sense by the 

 members of the medical profession, that animal 

 chemists have had great difficulty in fixing on 

 any distinctive characters by which the sub- 

 stance might be identified. The great source 

 of confusion appears to have been that phy- 

 siologists and the profession generally have 

 applied the adjective mucous or mucoid 

 to certain forms of secreted matter; from 

 which circumstance the term mucus has 

 gradually advanced into substantive vse as a 

 medico-chemical word, embracing in its mean- 

 ing the secretions from the mouth, nose, in- 

 testines, &c. as though these were identical 

 in their chemical characters. We shall pre- 

 sently show, however, that such is not the case. 



In the Philosophical Transactions for 1800 

 Mr. Hatchett published a paper, in which he 

 endeavoured to show that such a principle 

 as mucus really existed, characterised by pecu- 

 liar properties; but considered it a modified 

 form of gelatin. Dr. Bostock subsequently 

 published a paper in Nicholson's Journal, in 

 which he showed that mucus differed from 

 gelatin; this he proved by demonstrating that 



VOL. III. 



tanning did not precipitate mucus, though 

 gelatin was immediately thrown down by it, 

 whereas diacetate of lead precipitated mucus 

 copiously, without affecting gelatin : bichloride 

 of mercury and ferrocyanuret of potassa did 

 not precipitate either mucus or gelatin. I shall 

 show hereafter that these last-mentioned re- 

 actions do not apply to every form of mucus : 

 the ingenious experiments of Dr. Bostock can 

 indeed no longer be considered pertinent, in- 

 asmuch as the researches of modern chemists 

 have gone far to prove that gelatin is rather 

 a product than an educt of animal analysis. 

 The experiments of Dr. Bostock were made 

 on the saliva of the mouth, and some sub- 

 sequent observations by Mr. Brande made on 

 the same secretion showed that the precipitates 

 obtained by the diacetate of lead and nitrate 

 of silver consisted of the chlorides and phos- 

 phates of those metals; a fact which inclined 

 Mr. Biande to consider mucus as a compound 

 substance rather than a proximate element, and 

 induced him to apply electricity as a means of 

 decomposition. From the results obtained 

 in this inquiry, Mr. Brande was inclined to 

 consider mucus as a compound of albumen 

 either with pure soda or chloride of sodium. 



Dr. Marcet made some experiments on 

 mucus which induced him to believe that 

 several morbid secretions contained it as a 

 constituent ; he considered it to be present 

 in dropsical effusions. Berzelius, though he 

 allows the secretions of the mucous membranes 

 to differ in chemical character, and to possess 

 distinct properties according to the especial 

 office they have to fulfil in lubricating par- 

 ticular parts, still believes that such a proximate 

 element as mucus really exists as one of the 

 constituents of such secretions, and notices it 

 in his analysis of mucus of the nose. In 

 considering this subject it is, therefore, neces- 

 sary to premise that the general term, as used 

 by the medical profession, has no relation 

 whatever to the chemistry of the question, 

 the secretions of the different mucous mem- 

 branes varying greatly in chemical composition, 

 but, notwithstanding, presenting a physical 

 character in common, in relation to which 

 the term mucous has been applied to them. 

 The inquiry of greatest interest consists in 

 determining whether there exists a peculiar 

 proximate element in virtue of which the 

 mucous character is developed, or whether, on 

 the other hand, the peculiar physical character 

 can be traced to the presence of some combi- 

 nation of albumen which is common to all 

 mucous secretions, notwithstanding that they 

 may differ greatly in other respects. We have 

 already seen that the latter opinion is supported 

 by Mr. Brande's experiments, while Berzelius, 

 on the contrary, seems to favour the former 

 view of the case. Before entering upon this 

 question I shall describe the chemical characters 

 of several secretions from mucous surfaces, as 

 the reader will then be better prepared for the 

 inquiry. I shall commence with the secretion 

 from the nose, since this may be regarded as 

 the type of those viscous products to which 

 the general name of mucus has been applied. 



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