64 CONTRACTILE FIBRE-CELLS. 



had been carefully examined with reference to their histological 

 elements, without our recognising these cellular parts as identical 

 with organic muscular fibres ; especially in the tunica dartos, in the 

 middle coat of the arteries, in the choroid coat of the eye, in 

 the veins and lymphatics, in the corpora cavernosa, the prostate 

 gland, the Fallopian tubes, the uterus and urethra ; also in many 

 mucous membranes, and especially around the intestinal villi 

 (Briicke). In the trachea, the bronchi, the ureters and vasa 

 deferentia, as well as in the internal muscular tunic of the testicle, 

 they approximate more closely to the pure smooth muscles. Finally, 

 the smooth muscles are never enclosed by a true sarcolemma. 



These histological structures do not serve the animal organism 

 by their physical properties like the elastic fibres, in conjunction 

 with which they so frequently occur; but it is to them that those 

 tissues, in which they were formerly either only imperfectly, or not 

 at all recognised, owe their contractility under the influence of the 

 nervous system. The admirable labours of Ed. Weber* have 

 yielded us the most valuable information in reference to this sub- 

 ject, and have clearly elucidated the essential differences existing 

 between the action of the contractile organs and that of the animal 

 muscles. Weber has shown that in the case of almost all the 

 organs which are provided with these cell-fibres, a mechanical or 

 chemical irritant, such, for instance, as the employment of a 

 galvanic current, generated by the rotatory apparatus, induced only 

 a gradual, and, at first, a very limited contraction, which, however, 

 became diffused, after a time, over a larger portion of the part in 

 question. Neither the bundles touched by the pole, nor the parts 

 depending upon the excited nerves, contracted in any very appre- 

 ciable period after the application and interruption of the galvanic 

 current, but the adjacent bundles became successively affected, and 

 a movement was thus induced which did not finally disappear for 

 a long time. Ed. Weber succeeded, both independently and 

 in conjunction with E. H. Weber,| in detecting the contractions 

 in veins and arteries of medium and small calibre in nearly the 

 same forms as they occur in other organs. KollikerJ also has re- 

 cently observed them in the blood-vessels and lymphatics of man. 



Ecker and K611iker|| have, however, fully shown, by com- 



* Handworterbuch der Physiologie. Bd. 3, Abth. 2, S. 1-122. 

 f Berichte der k. sachs. Gess. d. Wiss. 1849. S. 91-96. 

 $ Zeitsch. f. wiss. Zool. Bd. 1, S. 257-260. 

 Ibid. pp. 218-245. 

 || Op. cit. pp. 213-217. 



