728 EXAMINATION OF STRIATED MUSCULAR FIBRE. 



into its component fibres ; and these, if possible, should be sepa- 

 rated into their fibrillar, by dissection with a pair of needles under 

 the Simple Microscope. The general characters of the Striated 

 Fibre are admirably shown in the large fibres of the Frog; and by 

 selecting a portion in which these fibres spread themselves out to 

 unite with a broad Tendinous expansion, they may often be found 

 so well displayed in a single layer, as not only to exhibit all their 

 characters without any dissection, but also to show their mode of 

 connection with the Simple Fibrous tissue of which that expansion 

 is formed. As the ordinary characters of the Fibre are but little 

 altered by boiling, this process may be had-recourse-to for their 

 more ready separation, especially in the case of the Tongue. The 

 separation of the fibres into their fibrillar is only likely to be 

 accomplished, in the higher Vertebrata, by repeated attempts, of 

 which the greater number are likely to be unsuccessful ; but it 

 may be accomplished with much greater facility in the Eel and 

 other Fish, the tenacity of whose muscular tissue is much less. 

 The characters of the fibrillse are not nearly so well pronounced, 

 however, in the Fish, as in the warm-blooded Vertebrata ; and 

 among the latter, the Pig has been found by Mr. Lealand (who 

 has been peculiarly successful in this class of preparations) to yield 

 the best examples. He lays great stress on the freshness of the 

 specimen, which should be taken from the body as soon as possible 

 after death ; and when a successful preparation has been made, he 

 preserves it in Goadby's solution. Dr. Beale, however, recommends 

 Glycerine for the preparation, and Glycerine-media for the preser- 

 vation, of objects of this class ; and states that the alternation of 

 light and dai'k spaces in the Fibrillse is rendered more distinct by 

 such treatment. The Fibrillar are often more readily separable 

 when the Muscle has been macerated in a weak solution of Chromic 

 Acid. — The shape of the Fibres can only be properly seen in cross 

 sections ; and these are best made by partially drying a piece of 

 muscle, so that very thin slices can be cut with a sharp instrument, 

 which, on being moistened again, will resume in great part their 

 original characters. — Striated Fibres, separable with great facility 

 into their component Fibrillae, are readily obtainable from the 

 limbs of Crustacea and of Insects ; and their presence is also 

 readily distinguishable in the bodies of Worms, even of very low 

 organization ; so that it may be regarded as characteristic of the 

 Articulated series generally. On the other hand, the Molluscous 

 classes are for the most part distinguished by the non-striation of 

 their fibre ; there are, however, two remarkable exceptions, strongly 

 striated fibre having been found in the Terebratula and other 

 Brachiopods (where, however, it is limited to the Adductor muscles 

 of the shell), and also in many Polyzoa. Its presence seems always 

 related to energy and rapidity of movement ; whilst the non-striated 

 presents itself where the movements are slower and feeblerjn their 

 character. 



