88 TEXT-BOOK OF PHYSIOLOGY 



ments. The same holds true of the bladder muscle of the cat, the muscle 

 of the ureter, etc. Careful observation shows a certain periodicity in the 

 movements. Inasmuch as the cause is not apparent, these contractions 

 are termed spontaneous or automatic. 



Graphic Record of the Contraction. For experimental purposes 

 narrow transverse sections of the stomach of the frog or the entire bladder 

 muscle of the cat, excised or in situ, according to the method of Prof. Colin 

 C. Stewart, may be employed. If kept moist, they will retain their irritability 

 for some hours. The changes of form may be recorded with the usual 

 muscle lever. When thus prepared, the muscle may exhibit for several 

 hours a series of pulsations, rhythmic in character. With spontaneously 

 acting mammalian muscle the contraction and relaxation periods are of 

 equal duration. With the amphibian muscle they are of unequal duration, 

 as a rule. In both classes of animals the character of the record, a suc- 

 cession of large and small contractions, would indicate that the general 

 rhythmic movement is compounded of two or three secondary rhythms 

 which differ in rate and character. A single pulsation may be recorded 

 by stimulating the bladder muscle with the induced or the make and break 

 of the constant current. A curve of such a contraction is shown in Fig. 41 . 

 The contraction takes place more rapidly than the relaxation; the two 

 phases occupying five and thirty-five seconds respectively. The latent 

 period covered 0.25 second. With other muscles the time relations are 

 slightly different. Tetanization of the bladder muscle of the cat occurred 

 when the stimuli succeeded each other with a certain rapidity; the interval 

 between stimuli approximating a period somewhat less than two seconds. 

 This muscle responds to variations in temperature, to strength of stim- 

 ulus, to the load, in a manner similar to, if not iden- 

 tical with, the skeletal muscle. 



The Function of the Visceral Muscle. In a 

 general way it may be said that the visceral muscle 

 determines and regulates the passage through the 

 viscus or organ of the material contained within it. 

 The food in the stomach and intestines is subjected 

 to a churning process by the muscles, in consequence 

 of which the digestive fluids are more thoroughly in- 

 corporated and their characteristic action increased. 



At the same time the food is carried through the 



canal, the absorption of the nutritive material pro- 

 FIG. 41. THE CURVE moted, and the indigestible residue removed from the 



OF CONTRACTION OF THE body. The blood is delivered in larger or smaller 

 BLADDER MUSCLE AT , ,. ,, , ,, .9 i 



BODY-TEMPERATURE IN volumes according to the needs of the tissues through 



RESPONSE TO A SINGLE a relaxation or contraction of the muscle-fibers of the 

 INDUCTION CURRENT, blood-vessels. The urine is forced through the ureter 



THE TIME IS INDICATED . , . . . . . . . 



IN SECONDS. (Stewart.) ano - from the bladder by the contraction of their re- 

 spective muscles. The mode of action of the individ- 

 ual muscles will be described in successive chapters. 



Ciliary Movement. The free surface of the epithelium covering the 

 mucous membrane in certain regions of the body is characterized by the 

 presence of delicate filamentous processes termed cilia. (See Fig. 42.) 

 Ciliated epithelium is found in man and mammals generally, in the nose, 



