122 HOW TO WORK 



The true nature of these bodies has been already explained in 

 page 78. Lacunae with their masses of living or germinal matter 

 are represented in fig. 180, pi. XXVII. 



In pi. XXVII, fig. 179, a drawing is given showing cartilage and 

 tendon continuous with it. The white fibrous tissue of the tendon 

 is seen to be continuous with the so-called matrix or intercellular 

 substance of the cartilage, and fig. 181, represents the changes 

 taking place in the development of bone of a mammalian animal. 

 These figures are worthy of very attentive study. 



Examination of the Higher Tissues. 



219. Examination of Muscular Fibre. For a full description of the 

 minute anatomy of muscular fibre, I must refer to the various works 

 on physiology and minute anatomy ; and especially to the well-known 

 papers of Mr. Bowman in the Philosophical Transactions, 1840-41, 

 and to the articles " Muscle," and " Muscular Motion," in the Cyclo- 

 pedia of Anatomy and Physiology. 



Two forms of muscular fibre have been described, the striped or 

 voluntary fibre, or muscular fibre of animal life, and the unstriped, 

 involuntary, or muscular fibre of organic life, the characters of which 

 will be presently referred to. Both forms possess inherent con- 

 tractility, but each contracts when touched, as may be proved by 

 direct experiment under the microscope, or when the nerve fibres 

 ramifying over it are touched or irritated in any other manner. The 

 voluntary muscle alone is under the direct control of the will, while 

 the involuntary fibre performs its functions altogether independently 

 of volition, but both are very freely supplied with nerve fibres which 

 ramify amongst the muscular fibres forming networks or plexuses 

 around them. 



Striped muscular fibre may be obtained from the voluntary 

 muscles of man or any animal. If specimens be taken from the 

 members of the different vertebrate classes, certain characteristic 

 peculiarities will be met with, and the muscular fibre of the crustacean 

 mollusc, or insect, differs from that of the higher animals in many im- 

 portant particulars, 



In order to subject a portion of muscular fibre to microscopical 

 examination, it is only necessary to remove a small piece with a sharp 

 knife or a pair of scissars. After tearing it up with needles, and 

 moistening it with a drop of water, the thin glass cover may be placed 

 on it, and the specimen examined with different powers. The 

 transverse striae will often be rendered very distinct after the fibre has 

 been allowed to macerate for some time in glycerine. 



The general arrangement and form of the fibres in voluntary 



