66 MUSCULAR TISSUE. 



such a preparation it is seen that a meshwork is formed by the 

 repeated division of the bundles of fibres. If the bit is soaked 

 for a few minutes in one 'per cent, or two per cent, acetic acid, 

 the epithelium brushed off with a camel-hair pencil, and the 

 membrane then examined in water or glycerin, the individual 

 elements of the muscular bundles come very distinctly into 

 view ; those of the muscular coats of the arteries can also be 

 studied advantageously. The mesentery of the newt maybe 

 prepared in the same manner. Instructive preparations of 

 muscular tissue may be obtained by carefully excising the iris 

 of an albino rabbit just killed, and spreading it flat on the ob- 

 ject glass in an indifferent liquid. The muscular tissue of the 

 intestine can be prepared as follows : A short portion of the 

 small intestine of a rabbit, or mature foetus, is filled with half 

 per cent, salt solution by ligaturing one of the ends, and tying 

 into the other a glass tube with a canulated extremity, through 

 which the liquid must be injected. The gut having been in 

 this way well distended, a second ligature is placed between 

 it and the canula. Thin shreds, consisting only of the perito- 

 neum and of the longitudinal muscular layer, are then stripped 

 off with the aid of pointed forceps from the surface of the in- 

 testine opposite to its meseuteric attachment. These strips 

 are carefully spread out and prepared in an indifferent liquid. 

 Of course care must be taken not to pierce the intestine with 

 the forceps. Another suitable object of stucVy is the abdominal 

 extremity of the Fallopian tube, which, in some mammalia 

 (e. g., in the sow), is dilated into a large thin sac. It may be 

 prepared in the same way as the bladder of the frog. An ex- 

 cellent method of preparing unstriped muscle is to immerse the 

 tissue in half per cent, solution of gold, for which purpose the 

 bladder of the frog, the mesentery of the newt, the iris of the 

 eyes of albino animals, or the muscular coat of the intestine 

 of small mammalia may be used. The bladder of the frog is 

 prepared as follows : A frog is decapitated, and the upper 

 two-thirds of the abdominal cavity opened. A solution of chlo- 

 ride of gold is injected, either "by means of a tube ten to fifteen 

 centimetres in length, which is drawn out at one end so as to 

 form a canula, and bent at an obtuse angle so as to facilitate 

 its introduction into the bladder, or, still better, with the aid 

 of a glass syringe furnished with a long beak. As soon as the 

 bladder is filled; a ligature is placed round its neck and tight- 

 ened round the canula, after which the organ may be excised 

 and placed in a capsule, containing a similar solution, for fif- 

 teen minutes. After this time it is cut into small sections, 

 which are immersed in acidulated water and exposed to the 

 light. If this method is followed, there is no fear of folds or 

 shrinking, as the bladder is already more or less hardened. 

 As soon as the fragments have acquired a dark violet or dull 



