522 MOVEMENTS. 



CHAPTEK XVI. 



MOVEMENTS VOICE AND SPEECH. 



Amorphous contractile substance Ciliary movements Movements due to elasticity Varieties of clastic tissue- 

 Muscular movements Physiological anatomy of the involuntary muscles Mode of contraction of the invol- 

 untary muscular tissue Physiological anatomy of the voluntary muscles Fibrous and adipose tissue in the 

 voluntary muscles Connective tissue Blood-vessels and lymphatics of the muscular tissue Connection of 

 the muscles with the tendons Chemical composition of the muscles Physiological properties of the mus- 

 clesMuscular contractility, or irritability Muscular contraction Changes in the form of the muscular 

 fibres during contraction Secousse, Ziickung, or spasm Mechanism of prolonged muscular contraction- 

 Tetanus Electric phenomena in the muscles Muscular effort Passive organs of locomotion Physiological 

 anatomy of the bones Marrow of the bones Medullocells Myeloplaxe-s Periosteum Physiological anatomy 

 of cartilage Fibro-cartilage Voice and speech Sketch of the physiological anatomy of the vucal organs- 

 Vocal chords Muscles of the larynx Mechanism of the production of the voice Appearance of the glottis 

 during ordinary respiration Movements of the glottis during phonation Variations in the quality of the 

 voice, depending upon differences in the size and form of the larynx and the vocal chords Action of the 

 intrinsic muscles of the larynx in phonation Action of the accessory vocal organs Mechanism of the differ- 

 ent vocal registers Mechanism of speech. 



THE organic, or vegetative functions of animals involve certain movements; and 

 almost all animals possess, in addition, the power of locomotion. Very many of these 

 movements have, of necessity, been considered in connection with the different functions ; 

 as the action of the heart and vessels in the circulation, the uses of the muscles in respi- 

 ration, the ciliary movements in the air-passages, the muscular acts in deglutition, the 

 peristaltic movements, and the mechanism of defalcation and urination. There remain, 

 however, certain general facts with regard to various kinds of movement and the mode 

 of action of the. different varieties of muscular tissue, that will demand more or less 

 extended consideration. As regards the exceedingly varied and complex acts concerned 

 in locomotion, it is difficult to fix the limits between anatomy and physiology. A full 

 comprehension of such movements must be preceded by a complete descriptive anatomi- 

 cal account of the passive and active organs of locomotion ; and special treatises on 

 anatomy almost invariably give the uses and actions, as well as the structure and rela- 

 tions of these parts. 



Amorphous Contractile Substance and Amoeboid Movements. In some of the very' 

 lowest orders of beings, in which hardly any thing but amorphous matter and a few gran- 

 ules can be recognized by the microscope, certain movements of elongation and retrac- 

 tion of their amorphous substance have been 

 observed. In the higher animals, similar 

 movements have been noticed in certain of 

 their structures, such as the leucocytes, the 

 contents of the ovum, epithelial cells, and 

 connective-tissue cells. These movements 

 are generally simple changes in the form 

 of the cell, nucleus, or whatever it may be. 

 FIG. UR.-Amaiba diffluens, changing in form ^d The ? are supposed to depend upon an organic 

 ^ng^ntte direction indicated ly the arrow, principle called sarcode or protoplasm; but 



it is not known that such movements are 



characteristic of any one definite proximate principle, nor is it easy to determine their 

 cause and their physiological importance. In the anatomical elements of adult animals 

 of the higher classes, the sarcodic movements usually appear slow and gradual, even 

 when viewed with high magnifying powers ; but, in some of the very lowest orders of 

 beings, these movements serve as the means of progression and are more rapid. Such 

 movements are sometimes called amoeboid. 



It does not seem possible, in the present condition of our knowledge, to explain the 



