108 GENERAL ANATOMY OF THE TISSUES. 



the peculiar cartilaginous striae, which Purkinje (Mikr. neurol. Beobach- 

 tungen, in Mull. "Arch.," 1845) found in the endocardium of Ruminants. 

 They consist of large polygonal cells with beautiful nuclei, which in- 

 ternally, but as it seems only upon their wall, contain a transversely 

 striated substance, which is not distinguishable from that in the muscular 

 fibres. 



All these forms are readily comprehended, if the genesis of the true 

 transversely striated muscular fibres in the higher vertebrata be properly 

 understood (see the special part, Muscles) ; and I cannot agree with the 

 supposition of Stannius (Gott. Nachr., 1851, p. 17), that the transversely 

 striated muscular fibrils are developed according to many essentially 

 different types. Even the gap which has hitherto separated the smooth 

 from the transversely striated muscles becomes less, when we remember 

 that the so-called transversely striated muscular fibrils may also have 

 homogeneous non-striated contents, and also that even when transversely 

 striated they may appear as isolated cells.* 



Muscular fibres of the same description as the transversely striated 

 muscles, and in part actually striated, are very widely distributed. In 

 the Vertebrata such muscles are found in the oesophagus of some Mam- 

 malia and of the plagiostome fishes, in the intestine of Tinea chrysitis, 

 in the stomach of Cobitis fossilis, around the poison gland of Snakes, 

 and in the contractile organ of the pharynx of the Carp ; in the skin of 

 Mammalia, Birds, Snakes, and tailless Batrachians (so called cutaneous 

 muscles), in the tactile hairs of mammals, in the lymph hearts of many Birds 

 and Amphibia ; in the auriculo-ventricular valve of the right side in Birds, 

 and the Ornithorhynchus ; upon the vena cava inferior of the Seal, 

 close above the diaphragm : in the interior of the eye of Birds ; and round 

 Cowper's and the anal glands of mammals. In the Invertebrata, as we 

 have mentioned, all the muscles belong to this category, whether they 

 be transversely striated or not ; and they are found, therefore, in the 

 heart, the intestine, the genitalia, and often clearly striated. 



The anastomosis of the primitive bundles of the muscles, with which 

 Leeuwenhoek was already acquaintedf and which I rediscovered in the 

 heart of the frog, has now been seen in many places, and appears to be 

 constant in the hearts of the lymph and blood-vascular systems of all 

 animals, and in the muscles of the Invertebrata, especially those of the 

 vegetative and generative organs. (Hessling, Leydig.) Simple arbores- 



* [The muscles of the Medusae consist of flat, fusiform bands, whose ends are interlaced 

 like those of smooth muscle, but which present the most distinct transverse striie. TRS.] 



j- [It has been pointed out to us by Professor Sharpey, that Leeuwenhoek was not 

 acquainted with the anastomosis of the primary bundles of the cardiac muscles, but has 

 described and figured only that of the secondary bundles, which is indeed obvious upon 

 reference to Leeuwenhoek's Plate (" Experimenta et Contemplationes," Op. Om. Lugd.Bat. 

 torn. i. p. 409, 1722); the ascription in the text is therefore an error. For other remarks upon 

 the muscular tissue, vide infra, Muscle. TRS.] 



