BY DR. KLEIN. 05 



foetus is best adapted, after having been steeped in Miillcr's 

 liquid, or in one-quarter to half per cent, solution of chromic 

 acid, for a few days. The sections may be stained with car- 

 mine (see Chapter VI.). For studying the development and 

 growth of bone in the epiphyses, longitudinal sections may 

 be made through the epiphysis of the femur, or of the tibia. <>f 

 the metacarpal bones, or phalanges of newly born human 

 foetuses, or of young rabbits. 



CHAPTER IY. 



MUSCULAR TISSUE. 



SECTION I. UNSTRIPED MUSCLE. 



THE elements of this tissue are cells the so-called " contrac- 

 tile fibre-cells" of varying length, and for the most part 

 spindle-shaped, this form being often modified by a flattening 

 of the cells where they come in contact. Their ends are either 

 single or divided. Their substance is, in the fresh state, a pale 

 or finely granular protoplasm, sometimes longitudinally stri- 

 ated: in the thicker part of the cell lies an oblong, compressed 

 nucleus, rather rounded at the extremities (thus becoming 

 staff-shaped), or pointed. The nucleus contains one or two 

 large shining nucleoli : if single, the nucleolus lies in the centre 

 of the nucleus ; if double, one is found at each extremit}'. 

 External to the nucleus, and in a straight line with its longi- 

 tudinal axis, some small granules may sometimes be seen. 

 The unstrip'ed muscular fibres are always arranged in bundles, 

 the elements .of which are separated from each other by inter- 

 stitial substance. The bundles are held. together by.connectivc 

 tissue, in which they lie in such a way that they either form 

 membranes (as in the intestine) or meshworks (as in the blad- 

 der). In the former rase, the bundles are parallel and mostly 

 undivided ; in the latter, they run in various directions, divide 

 frequently, and intercommunicate with each other. 



The best materials for the study of involuntary muscular 

 fibre, are the bladder of the frog, the mesentery of the newt, the 

 muscular coats of the intestines of the frog and mammalia, and 

 arteries, such as those at the root of the mesentery of the frog. 

 They may be demonstrated either in connection or isolated. 



To show their arrangement, a portion of the bladder of the 

 frog may be spread on the glass slide with the mucous surface 

 downwards, and covered in half per cent, salt solution. In 

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