MUSCLE. 



[ 447 ] 



MYRIAPODA. 



Fig. 507. 



Termination of the branches of a nerve in a portion of 

 the omohyoideus muscle, treated with caustic soda. 

 a, meshes of the terminal plexus ; b, loops ; c, muscular 

 fibres. 



Magnified 350 diameters. 



brata, and some of the Invertebrata, agrees 

 essentially in structure with that of man ; 

 but the sarcolemma is often much thicker, 

 the fibrillae larger, and the nuclei contained 

 within the substance of the bundles, and 

 sometimes arranged in regular linear series. 

 The margins of the bundles are also some- 

 times uneven, and rounded at regular inter- 

 vals (PI. 1/. fig. 35), giving the appearance 

 of their being surrounded by fibres. 



In many of the lower members of the In- 

 vertebrata, although the substance of the 

 body is voluntarily contractile, no trace of 

 bundles or fibres can be detected. 



To obtain the separate fibrillae of striated 

 muscle, the tissue should be macerated for 

 about two hours in alcohol. This removes 

 any fatty matter, and renders the fibrillae 

 more easily separable, by dissection with 

 mounted needles. The fibrillae are very 

 minute, as we have stated; hence a very 

 small portion of the tissue only should be 

 taken for examination. That of fishes (the 

 cod or the skate) or of reptiles (the frog) is 

 the best for the purpose. 



The unstriated muscular fibres are best 

 seen in muscle which has been treated with 



diluted nitric or muriatic acid ( 1 part acid to 

 4 water). This renders them more opaque, 

 and often curiously tortuous or spiral (fig. 

 502). 



BiBL. Kolliker, Mikrosk. Anat. ii. and 

 the Bibl. ; Henle, Allgem. Anat. ; Bowman, 

 Todd's Cycl. iii. art. Muscle, and Phil. 

 Trans. 1840 — W ; Donders, Mulder's 

 Physiolog. Chem. ; and the Bibl. of Che- 

 mistry, ANIMAL. 



MUSHROOMS. See Agaricus. 



MUSSEL. — The species of Mollusca 

 commonly known as mussels are of interest 

 to the microscopist, on account of their ali- 

 mentary canal containing Diatomacese ; the 

 same probably applies also to other marine 

 and aquatic Mollusca, as well as other ani- 

 mals living upon these minute Algae. 



If it be required to obtain the valves only, 

 the entire animal may be dissolved in hot 

 nitric acid, and the residue washed as usual 

 in preparing the Diatomaceae. 



The gills of the common marine mussel 

 [Mytilus edulis) are well adapted for the 

 examination of the cilia and ciliary motion. 



Mussels also frequently contain the 

 * nurses' and larvae {Cercarice) oi Distoma 

 and other Trematoda (Entozoa). 



One of the Acarina, Hydrachna (?) con- 

 charum (or Limnochares (?) anodontce), is 

 found in the pallial cavity or beneath the outer 

 lamella of the branchial plates of the Naia- 

 deae {Unio, &c.). 



Bibl. Dickie, A7in. Nat. Hist. 1848. i. 

 p. 322 ; Vogt, Ann. des Sc. nat. 3 ser. xii. ; 

 and the Bibl. of Mollusca. 



MYCOTHAMNION, Kiitz. — One of 

 Kiitzing's genera of Leptomiteous Algae, 

 composed of obscure byssoid productions 

 growing in foul water. Probably the mycelia 

 of fungi. 



MYOBIA, Heyd. See Acarina, p. 4. 



MYRIAPODA.— An order of Insects. 



Char. Wings absent ; legs numerous ; 

 thorax not separated from the abdomen. 



These animals are commonly know^n as 

 centipedes or millipedes. 



The body is usually long, cylindrical 

 or flattened, and consisting of numerous 

 rings or joints. The head distinct, and the 

 jointed legs arranged on each side of the 

 body throughout its length. A few of them 

 are broad, short, and flattened, somewhat 

 resembling wood-lice. The head is furnished 

 with a pair of antennse. Behind these are 

 laterally placed the eyes, which in some are 

 absent ; they consist of mostly a group of 

 ocelli. 



