MUSCULAR TISSUE. 41 



BLOOD-VESSELS OF MUSCLE. 



PREPARATION. Make longitudinal and transverse sections of any muscle of a cat or 

 other animal whose blood-vessels have been injected with a carmine or Prussian blue and 

 gelatine mass (p. li). The sections may be very slightly stained in logwood, or mounted 

 unstained in dammar, or a small piece of the muscle may be simply teased and mounted in 

 Farrant's solution. 



EXAMINATION of a longitudinal section (L). Observe the capillaries arranged parallel to 

 the long axis of the fibres one capillary between each two fibres, with here and there trans- 

 verse branches connecting them. They lie outside the muscular fibres and amongst the 

 delicate connective tissue which supports them. {Indicate the arrangement of the capillaries in 

 PI. VII., Fig. 13.) 



Transverse section (L). Observe the cut ends of the fibres and between and outside the 

 sarcolemma the cut ends of the capillaries. The larger blood-vessels lie in the connective tissue 

 of the perimysium. 



It is advisable to inject the blood-vessels of the lower limbs of a rabbit with a Prussian 

 blue and gelatine mass. Place the limbs in a one per cent, solution of bichromate of potash. 

 After the mass has set, select one of the red muscles, e.g. the semi-tendinosus. Most of the 

 muscles of the rabbit are pale or almost colourless. The above-mentioned muscles, and some 

 others (soleus, adductor minus, muscles of the jaw), are, however, distinctly red ; the semi-tendi- 

 nosus, at least, has a peculiar distribution of its blood-vessels. Tease out a small piece of one 

 of the injected red muscles and mount it in glycerine or dammar. 



EXAMINATION (L). The blood-vessels have the same distribution and relations as 

 described above, but they present this peculiarity that on the transverse, short capillaries are 

 small dilatations like little aneurysmal swellings. These swellings do not exist in the blood- 

 vessels of the pale muscles of the same animal. Further, the capillaries usually pursue a 

 more tortuous course, and the veins, also, sometimes present similar fusiform swellings in 

 their course. 



The muscular fibres of the heart will be examined in connection with that organ (p. 47); 

 and the nerves of muscles with the terminations of nerve-fibres (p. 45). 



Fcetal developing muscle may be studied in any embryo after hardening in Miiller's fluid. 

 It is characterised by the great number of its nuclei, the smallness of the fibres, and the im- 

 perfect striation. In fresh fcetal muscle iodine solution reveals the presence of glycogen. 



RELATION OF MUSCLE TO TENDON. 



PREPARATION (a). Centrum tendineum of the diaphragm. Cut out the diaphragm from a 

 newly killed rabbit ; place it in lemon juice for five minutes, and, after steeping in one per 

 cent, gold chloride for an hour, transfer to a twenty-five per cent, solution of formic acid for 

 twenty-four hours. During this time the preparation must be kept in the dark till the gold 

 is reduced. Snip out a small piece of the muscle, with the central tendon attached, and 

 tease it in glycerine on a slide and cover ; or a section may be made parallel with the long 

 axis of the muscular fibres. 



EXAMINATION (Land H). Observe the transversely striped muscle, and trace it towards 

 the tendon, where it ends abruptly in a conical form which is lodged in a corresponding 

 depression in the tendon. 



