TISSUES, ORGANS, AND SYSTEMS. 105 



exist, and also, that they are to be found in many localities in which 

 their presence had not been suspected. These views, notwithstanding 

 contradiction at first from certain quarters, are now universally con- 

 firmed ; a result to which Reichert, by the discovery of a reagent, which 

 readily enables even those who are less practised, easily to isolate the con- 

 tractile fibre-cells, viz. : nitric and hydrochloric acids of 20 per cent. 

 (Miiller, " Archiv," 1849, and Paulsen, " Obs. Microchem.," 1849) ; 

 and Lehmann, by his chemical investigations upon this tissue, have 

 contributed their share. Contractile fibre-cells occur in all four classes 

 of the Vertebrata, but appear to be wholly wanting in the Invertebrata, 

 since the smooth fibres of these creatures, which have been thought to 

 be such, are allied genetically to the transversely striated muscles of the 

 higher animals. 



Their occurrence in the Vertebrata is in some respects peculiar, 

 and I will here mention the following localities in which they are found : 

 In the skin of Birds, as the muscles of the quill-feathers in this case 

 with tendons of elastic tissue ; in that of the Orang-outang, in the hair- 

 sacs, as in man ; in the iris of the Amphibia ; in the campanula Hal- 

 leri of the osseous Fishes (Leydig); in the swimming bladder of Fishes; 

 in the lungs of the Frog (in Triton they are here wanting) ; in the me- 

 sentery of the Plagiostomata, or Psammosaurus and Leposternon (Ley- 

 dig u. Briicke) ; in the genito-rectal muscle of Mammals. In the giz- 

 zard of birds these muscles are of a bright red color, and are united 

 with a tendinous membrane. 



Literature. Kblliker, "Ueber den Bau und die Verbreitung der 

 glatten Muskeln.," in the " Mittheilungen der Naturf. Gesellschaft in 

 Zurich," 1847, p. 18, and " Zeitschrift fur wiss. Zool.," Bd. I. 1849; 

 C. R. Walther, " Nonnulla de musculis laevibus.," Diss. Lips. 1851.* 

 [Jos. Lister, " Observations on the Contractile Tissue of the Iris," 

 Quart. Journ. Mic. Sc., vol. I. p. 8, PL i., and " Observations on the 

 Muscular Tissue of the Skin," Quart. Journ. Mic. Sc. vol. I. p. 263. 

 DaC.] 



* [Reichert (Bericht, 1849, Miiller, " Archiv.,'') states that, according to Paulsen, the action 

 of a solution of caustic potass of 50 per cent, causes the smooth muscles to become wavy, 

 and thus to assume a transversely striated appearance under the microscope. Macerated 

 in such a solution for three days, they break up into small globules; striated muscle behaves 

 in a similar manner, and the globules correspond in size to the interval between two striae. 



Eylandt (Obs. Microscop. de musculis organicis in hominis cute obviis. Diss. inaug., Dorp. 

 1850, c. Tab. lithog.), denies the existence of free smooth muscles in the papilla and areola 

 nianitnce, in the scrotum, in the skin of the penis or of the prepuce, and in the perinaeum. Nor does 

 he find them in the outer layers of the hair-sacs (apart from the arrectores pili), in the glan- 

 dulce sudorifcree. of the axilla, of the anus, &c., nor in the glandula ceruminosce. The smooth 

 muscles observed in the papilla and areola niammce, in the skin of the penis, and the peri- 

 na um, he considers to belong to a greatly developed vascular layer. (See, however, the 

 remarks of Prof. Kolliker upon Eylandt's statements, at the end of 34.) TRS.] 



